<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.liveperson.com/role/AccruedLiabilitiesAndOtherCurrentLiabilities" xlink:href="lpsn-20191231.xsd#AccruedLiabilitiesAndOtherCurrentLiabilities" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/AccruedLiabilitiesAndOtherCurrentLiabilitiesDetails" xlink:href="lpsn-20191231.xsd#AccruedLiabilitiesAndOtherCurrentLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/AccruedLiabilitiesAndOtherCurrentLiabilitiesTables" xlink:href="lpsn-20191231.xsd#AccruedLiabilitiesAndOtherCurrentLiabilitiesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/Acquisitions" xlink:href="lpsn-20191231.xsd#Acquisitions" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/AcquisitionsNarrativeDetails" xlink:href="lpsn-20191231.xsd#AcquisitionsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CommitmentsAndContingencies" xlink:href="lpsn-20191231.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CommitmentsAndContingenciesEmployeeBenefitPlansDetails" xlink:href="lpsn-20191231.xsd#CommitmentsAndContingenciesEmployeeBenefitPlansDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CommitmentsAndContingenciesFutureMinimumLeasePaymentsUnderNonCancelableOperatingLeasesDetails" xlink:href="lpsn-20191231.xsd#CommitmentsAndContingenciesFutureMinimumLeasePaymentsUnderNonCancelableOperatingLeasesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CommitmentsAndContingenciesLeaseInformationDetails" xlink:href="lpsn-20191231.xsd#CommitmentsAndContingenciesLeaseInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CommitmentsAndContingenciesLeasesNarrativeDetails" xlink:href="lpsn-20191231.xsd#CommitmentsAndContingenciesLeasesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CommitmentsAndContingenciesTables" xlink:href="lpsn-20191231.xsd#CommitmentsAndContingenciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConsolidatedBalanceSheets" xlink:href="lpsn-20191231.xsd#ConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:href="lpsn-20191231.xsd#ConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConsolidatedStatementsOfCashFlows" xlink:href="lpsn-20191231.xsd#ConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConsolidatedStatementsOfComprehensiveLoss" xlink:href="lpsn-20191231.xsd#ConsolidatedStatementsOfComprehensiveLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConsolidatedStatementsOfOperations" xlink:href="lpsn-20191231.xsd#ConsolidatedStatementsOfOperations" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:href="lpsn-20191231.xsd#ConsolidatedStatementsOfStockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConvertibleSeniorNotesAndCappedCallTransactions" xlink:href="lpsn-20191231.xsd#ConvertibleSeniorNotesAndCappedCallTransactions" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConvertibleSeniorNotesAndCappedCallTransactionsCarryingAmountAndInterestExpenseDetails" xlink:href="lpsn-20191231.xsd#ConvertibleSeniorNotesAndCappedCallTransactionsCarryingAmountAndInterestExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConvertibleSeniorNotesAndCappedCallTransactionsNarrativeDetails" xlink:href="lpsn-20191231.xsd#ConvertibleSeniorNotesAndCappedCallTransactionsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/ConvertibleSeniorNotesAndCappedCallTransactionsTables" xlink:href="lpsn-20191231.xsd#ConvertibleSeniorNotesAndCappedCallTransactionsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CoverPage" xlink:href="lpsn-20191231.xsd#CoverPage" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPolicies" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesAccountsReceivableDetails" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesAccountsReceivableDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDeferredRevenueDetails" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDeferredRevenueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesReceivablesAndDeferredRevenueDetails" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesReceivablesAndDeferredRevenueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDisaggregationOfRevenueDetails" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDisaggregationOfRevenueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesReclassificationDetails" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesReclassificationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesRevenueByGeographicRegionDetails" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesRevenueByGeographicRegionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesTables" xlink:href="lpsn-20191231.xsd#DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurements" xlink:href="lpsn-20191231.xsd#FairValueMeasurements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueDetails" xlink:href="lpsn-20191231.xsd#FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsDerivativeFinancialInstrumentsDetails" xlink:href="lpsn-20191231.xsd#FairValueMeasurementsDerivativeFinancialInstrumentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsLevel3LiabilitiesDetails" xlink:href="lpsn-20191231.xsd#FairValueMeasurementsLevel3LiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsNarrativeDetails" xlink:href="lpsn-20191231.xsd#FairValueMeasurementsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsTables" xlink:href="lpsn-20191231.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssets" xlink:href="lpsn-20191231.xsd#GoodwillAndIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsChangesInCarryingAmountOfGoodwillDetails" xlink:href="lpsn-20191231.xsd#GoodwillAndIntangibleAssetsChangesInCarryingAmountOfGoodwillDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsSummaryOfAmortizationExpenseDetails" xlink:href="lpsn-20191231.xsd#GoodwillAndIntangibleAssetsSummaryOfAmortizationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails" xlink:href="lpsn-20191231.xsd#GoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsTables" xlink:href="lpsn-20191231.xsd#GoodwillAndIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/IncomeTaxes" xlink:href="lpsn-20191231.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/IncomeTaxesDomesticAndForeignComponentsOfIncomeBeforeProvisionForIncomeTaxesDetails" xlink:href="lpsn-20191231.xsd#IncomeTaxesDomesticAndForeignComponentsOfIncomeBeforeProvisionForIncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/IncomeTaxesNarrativeDetails" xlink:href="lpsn-20191231.xsd#IncomeTaxesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/IncomeTaxesScheduleOfFederalDeferredTaxAssetsAndDeferredTaxLiabilitiesDetails" xlink:href="lpsn-20191231.xsd#IncomeTaxesScheduleOfFederalDeferredTaxAssetsAndDeferredTaxLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/IncomeTaxesScheduleOfProvisionForIncomeTaxesDetails" xlink:href="lpsn-20191231.xsd#IncomeTaxesScheduleOfProvisionForIncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/IncomeTaxesScheduleOfReconciliationsOfFederalStatutoryTaxRateToEffectiveIncomeTaxRateDetails" xlink:href="lpsn-20191231.xsd#IncomeTaxesScheduleOfReconciliationsOfFederalStatutoryTaxRateToEffectiveIncomeTaxRateDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/IncomeTaxesScheduleOfUnrecognizedTaxBenefitsDetails" xlink:href="lpsn-20191231.xsd#IncomeTaxesScheduleOfUnrecognizedTaxBenefitsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/IncomeTaxesTables" xlink:href="lpsn-20191231.xsd#IncomeTaxesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/LegalMatters" xlink:href="lpsn-20191231.xsd#LegalMatters" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/NetLossPerShare" xlink:href="lpsn-20191231.xsd#NetLossPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/NetLossPerShareDetails" xlink:href="lpsn-20191231.xsd#NetLossPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/NetLossPerShareTables" xlink:href="lpsn-20191231.xsd#NetLossPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/PropertyAndEquipment" xlink:href="lpsn-20191231.xsd#PropertyAndEquipment" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/PropertyAndEquipmentBalancesDetails" xlink:href="lpsn-20191231.xsd#PropertyAndEquipmentBalancesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/PropertyAndEquipmentNarrativeDetails" xlink:href="lpsn-20191231.xsd#PropertyAndEquipmentNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/PropertyAndEquipmentTables" xlink:href="lpsn-20191231.xsd#PropertyAndEquipmentTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringCosts" xlink:href="lpsn-20191231.xsd#RestructuringCosts" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringCostsComponentsOfRestructuringChargesDetails" xlink:href="lpsn-20191231.xsd#RestructuringCostsComponentsOfRestructuringChargesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringCostsExpensesRelatedToRestructuringChargesDetails" xlink:href="lpsn-20191231.xsd#RestructuringCostsExpensesRelatedToRestructuringChargesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringCostsNarrativeDetails" xlink:href="lpsn-20191231.xsd#RestructuringCostsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringCostsTables" xlink:href="lpsn-20191231.xsd#RestructuringCostsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformation" xlink:href="lpsn-20191231.xsd#SegmentInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationLongLivedAssetsByGeographicRegionDetails" xlink:href="lpsn-20191231.xsd#SegmentInformationLongLivedAssetsByGeographicRegionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationNarrativeDetails" xlink:href="lpsn-20191231.xsd#SegmentInformationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationSummaryOfFinancialInformationBySegmentDetails" xlink:href="lpsn-20191231.xsd#SegmentInformationSummaryOfFinancialInformationBySegmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationTables" xlink:href="lpsn-20191231.xsd#SegmentInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquity" xlink:href="lpsn-20191231.xsd#StockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquityNarrativeDetails" xlink:href="lpsn-20191231.xsd#StockholdersEquityNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquitySummaryOfOutstandingAndVestedOptionsDetails" xlink:href="lpsn-20191231.xsd#StockholdersEquitySummaryOfOutstandingAndVestedOptionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquitySummaryOfRestrictedStockUnitActivityDetails" xlink:href="lpsn-20191231.xsd#StockholdersEquitySummaryOfRestrictedStockUnitActivityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquitySummaryOfStockOptionActivityAndWeightedAverageExercisePricesDetails" xlink:href="lpsn-20191231.xsd#StockholdersEquitySummaryOfStockOptionActivityAndWeightedAverageExercisePricesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquityTables" xlink:href="lpsn-20191231.xsd#StockholdersEquityTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquityWeightedAverageAssumptionsOfFairValueOptionsUsingBlackScholesOptionPricingModelDetails" xlink:href="lpsn-20191231.xsd#StockholdersEquityWeightedAverageAssumptionsOfFairValueOptionsUsingBlackScholesOptionPricingModelDetails" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/AccruedLiabilitiesAndOtherCurrentLiabilities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/AccruedLiabilitiesAndOtherCurrentLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/AccruedLiabilitiesAndOtherCurrentLiabilitiesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/Acquisitions" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/AcquisitionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_D6B1B39344C33EAF1540663FDA0C9BE5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_D6B1B39344C33EAF1540663FDA0C9BE5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_2F2A7401E84B2FB60C7966826C2BCC91" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_D6B1B39344C33EAF1540663FDA0C9BE5" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_2F2A7401E84B2FB60C7966826C2BCC91" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_1F218FBF66BB3D35248866826C364AF4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_2F2A7401E84B2FB60C7966826C2BCC91" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_1F218FBF66BB3D35248866826C364AF4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_1F218FBF66BB3D35248866826C364AF4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_2F2A7401E84B2FB60C7966826C2BCC91" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_1F218FBF66BB3D35248866826C364AF4" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ContingentEarnOutMember" xlink:label="loc_lpsn_ContingentEarnOutMember_F5737DEDEF2C10113AED66826C5347F2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_1F218FBF66BB3D35248866826C364AF4" xlink:to="loc_lpsn_ContingentEarnOutMember_F5737DEDEF2C10113AED66826C5347F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_3E3BD5AA7F647686E68A663FDA0DC4A2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_D6B1B39344C33EAF1540663FDA0C9BE5" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_3E3BD5AA7F647686E68A663FDA0DC4A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_15B1F5BD5B02007BADF8663FDA0DC539_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3E3BD5AA7F647686E68A663FDA0DC4A2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_15B1F5BD5B02007BADF8663FDA0DC539_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_15B1F5BD5B02007BADF8663FDA0DC539" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3E3BD5AA7F647686E68A663FDA0DC4A2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_15B1F5BD5B02007BADF8663FDA0DC539" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AdvantageTecIncMember" xlink:label="loc_lpsn_AdvantageTecIncMember_167D7F264B72E837201B663FDA0D2EFA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_15B1F5BD5B02007BADF8663FDA0DC539" xlink:to="loc_lpsn_AdvantageTecIncMember_167D7F264B72E837201B663FDA0D2EFA" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConversableIncMember" xlink:label="loc_lpsn_ConversableIncMember_90CA430CFF64DF79DEE3663FDA0DE5C3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_15B1F5BD5B02007BADF8663FDA0DC539" xlink:to="loc_lpsn_ConversableIncMember_90CA430CFF64DF79DEE3663FDA0DE5C3" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_BotCentralMember" xlink:label="loc_lpsn_BotCentralMember_84D24DD203EBED613E07667ECEE4A981" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_15B1F5BD5B02007BADF8663FDA0DC539" xlink:to="loc_lpsn_BotCentralMember_84D24DD203EBED613E07667ECEE4A981" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_597244D6962C2E1D98B9663FDA0E8F95" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_597244D6962C2E1D98B9663FDA0E8F95" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_655A3C2541249BC6F1A4663FDA0EBF0C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_655A3C2541249BC6F1A4663FDA0EBF0C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_AB3C12900673C1CDF56C663FDA0FFB25" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_AB3C12900673C1CDF56C663FDA0FFB25" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_PotentialEarnOutContingentConsiderationPaymentsTargetBased" xlink:label="loc_lpsn_PotentialEarnOutContingentConsiderationPaymentsTargetBased_3BE6FFF9D4BAF3DEA4FC663FDA0F4CF9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_lpsn_PotentialEarnOutContingentConsiderationPaymentsTargetBased_3BE6FFF9D4BAF3DEA4FC663FDA0F4CF9" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments" xlink:label="loc_lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments_F597A37F6FE4720569EF663FDA0E2732" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments_F597A37F6FE4720569EF663FDA0E2732" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" xlink:label="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_4886BC7A98BCD1F6933E663FDA0FDB5D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_4886BC7A98BCD1F6933E663FDA0FDB5D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillAcquiredDuringPeriod" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_136553AF00E2DF9A2ACE663FDA0F1AC7" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_136553AF00E2DF9A2ACE663FDA0F1AC7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts" xlink:label="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_01BB89F75CE0E3376C7E663FDA10B383" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_BusinessAcquisitionCostOfAcquiredEntityTransactionCosts_01BB89F75CE0E3376C7E663FDA10B383" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_8CBF853878D3DD642777663FDA0FA216" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_8CBF853878D3DD642777663FDA0FA216" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_7123894D7E9635480927663FDA1009E7" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E2E8E9CAA70E59733EBD663FDA0EA011" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_7123894D7E9635480927663FDA1009E7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CommitmentsAndContingenciesEmployeeBenefitPlansDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherCommitmentsLineItems" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_82C0B69E7DBBD1012DD666D47230C041" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherCommitmentsTable" xlink:label="loc_us-gaap_OtherCommitmentsTable_30456EE53D5BC1375B4666D472290BEB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_82C0B69E7DBBD1012DD666D47230C041" xlink:to="loc_us-gaap_OtherCommitmentsTable_30456EE53D5BC1375B4666D472290BEB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DefinedContributionPlanMatchGroupsAxis" xlink:label="loc_lpsn_DefinedContributionPlanMatchGroupsAxis_5142CCD364FC70B1978966D4724E8434" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_30456EE53D5BC1375B4666D472290BEB" xlink:to="loc_lpsn_DefinedContributionPlanMatchGroupsAxis_5142CCD364FC70B1978966D4724E8434" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DefinedContributionPlanMatchGroupsDomain" xlink:label="loc_lpsn_DefinedContributionPlanMatchGroupsDomain_BC13502EB463EEA90F1766D4E6E4CA32_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_lpsn_DefinedContributionPlanMatchGroupsAxis_5142CCD364FC70B1978966D4724E8434" xlink:to="loc_lpsn_DefinedContributionPlanMatchGroupsDomain_BC13502EB463EEA90F1766D4E6E4CA32_default" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DefinedContributionPlanMatchGroupsDomain" xlink:label="loc_lpsn_DefinedContributionPlanMatchGroupsDomain_BC13502EB463EEA90F1766D4E6E4CA32" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_lpsn_DefinedContributionPlanMatchGroupsAxis_5142CCD364FC70B1978966D4724E8434" xlink:to="loc_lpsn_DefinedContributionPlanMatchGroupsDomain_BC13502EB463EEA90F1766D4E6E4CA32" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_MatchingTrancheOneMember" xlink:label="loc_lpsn_MatchingTrancheOneMember_44FCD53013B82EE4DC5B66D4725DB168" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_DefinedContributionPlanMatchGroupsDomain_BC13502EB463EEA90F1766D4E6E4CA32" xlink:to="loc_lpsn_MatchingTrancheOneMember_44FCD53013B82EE4DC5B66D4725DB168" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_MatchingTrancheTwoMember" xlink:label="loc_lpsn_MatchingTrancheTwoMember_C9156D7066527F51BF8866D4726AD054" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_DefinedContributionPlanMatchGroupsDomain_BC13502EB463EEA90F1766D4E6E4CA32" xlink:to="loc_lpsn_MatchingTrancheTwoMember_C9156D7066527F51BF8866D4726AD054" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_79F8976B08283F82A71E66D4723E3C66" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_82C0B69E7DBBD1012DD666D47230C041" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_79F8976B08283F82A71E66D4723E3C66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_EF19B7959EF338393BBD663FD9D58B97" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_82C0B69E7DBBD1012DD666D47230C041" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent_EF19B7959EF338393BBD663FD9D58B97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_A9C66623570967ECB01A663FD9D5BE0C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_82C0B69E7DBBD1012DD666D47230C041" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_A9C66623570967ECB01A663FD9D5BE0C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DefinedBenefitPlanEmployersContributionOfVestingPeriod" xlink:label="loc_lpsn_DefinedBenefitPlanEmployersContributionOfVestingPeriod_1F6DA611315C2CB66ECD663FD9D5B156" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_82C0B69E7DBBD1012DD666D47230C041" xlink:to="loc_lpsn_DefinedBenefitPlanEmployersContributionOfVestingPeriod_1F6DA611315C2CB66ECD663FD9D5B156" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_A80FACA7B6937E1483F3663FD9D526F6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_82C0B69E7DBBD1012DD666D47230C041" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_A80FACA7B6937E1483F3663FD9D526F6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CommitmentsAndContingenciesFutureMinimumLeasePaymentsUnderNonCancelableOperatingLeasesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CommitmentsAndContingenciesLeaseInformationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CommitmentsAndContingenciesLeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_D80864044E5543D2FE5C8AA0CD14E45C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_68DB27C32F32AD4AFDBF8AA0CD139149" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_D80864044E5543D2FE5C8AA0CD14E45C" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_68DB27C32F32AD4AFDBF8AA0CD139149" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_7707E348AB625B442F1D8AA0CD13693A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_68DB27C32F32AD4AFDBF8AA0CD139149" xlink:to="loc_srt_RangeAxis_7707E348AB625B442F1D8AA0CD13693A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_0D808C472FC98F5088F88AA0CD13665F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7707E348AB625B442F1D8AA0CD13693A" xlink:to="loc_srt_RangeMember_0D808C472FC98F5088F88AA0CD13665F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_0D808C472FC98F5088F88AA0CD13665F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7707E348AB625B442F1D8AA0CD13693A" xlink:to="loc_srt_RangeMember_0D808C472FC98F5088F88AA0CD13665F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_D90EC2245E1BCEC896048AA0CD144BB6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0D808C472FC98F5088F88AA0CD13665F" xlink:to="loc_srt_MinimumMember_D90EC2245E1BCEC896048AA0CD144BB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_6C53B596091FC81D70F98AA0CD141A1D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_0D808C472FC98F5088F88AA0CD13665F" xlink:to="loc_srt_MaximumMember_6C53B596091FC81D70F98AA0CD141A1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LesseeOperatingLeaseTermOfContract" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_6569C7A1AC8382616BDF8AA0CD14BF08" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_D80864044E5543D2FE5C8AA0CD14E45C" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_6569C7A1AC8382616BDF8AA0CD14BF08" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_5910E4A31D8BCC3A39E18AA0CD157A21" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_D80864044E5543D2FE5C8AA0CD14E45C" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_5910E4A31D8BCC3A39E18AA0CD157A21" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability_5083A58EDF13F56215F68AA0CD1AEDAE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_D80864044E5543D2FE5C8AA0CD14E45C" xlink:to="loc_us-gaap_OperatingLeaseLiability_5083A58EDF13F56215F68AA0CD1AEDAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseExpense" xlink:label="loc_us-gaap_OperatingLeaseExpense_AC388590084DA94BC5A08AA0CD1A9F75" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_D80864044E5543D2FE5C8AA0CD14E45C" xlink:to="loc_us-gaap_OperatingLeaseExpense_AC388590084DA94BC5A08AA0CD1A9F75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeasePayments" xlink:label="loc_us-gaap_OperatingLeasePayments_04A52C349D74DF6C4CFC8AA78AED92EE" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_D80864044E5543D2FE5C8AA0CD14E45C" xlink:to="loc_us-gaap_OperatingLeasePayments_04A52C349D74DF6C4CFC8AA78AED92EE" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CommitmentsAndContingenciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConsolidatedBalanceSheets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConsolidatedStatementsOfCashFlows" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_5D51088450B163F1026D985E5CD37A5F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_StatementTable_5D51088450B163F1026D985E5CD37A5F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis_E0C3F23CE98AC5A1EE0A985E5CD3BE52" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_5D51088450B163F1026D985E5CD37A5F" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis_E0C3F23CE98AC5A1EE0A985E5CD3BE52" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionNameDomain" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis_E0C3F23CE98AC5A1EE0A985E5CD3BE52" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionNameDomain" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis_E0C3F23CE98AC5A1EE0A985E5CD3BE52" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConversableInc1Member" xlink:label="loc_lpsn_ConversableInc1Member_641E59706730B3355F15985E5CD40500" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9" xlink:to="loc_lpsn_ConversableInc1Member_641E59706730B3355F15985E5CD40500" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_BotCentralMember" xlink:label="loc_lpsn_BotCentralMember_FD961F60EF78BF2C76B9985E5CD48CC9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9" xlink:to="loc_lpsn_BotCentralMember_FD961F60EF78BF2C76B9985E5CD48CC9" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConversableInc2Member" xlink:label="loc_lpsn_ConversableInc2Member_A4AC6576D537CE2CDBC7985E5CD4C354" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9" xlink:to="loc_lpsn_ConversableInc2Member_A4AC6576D537CE2CDBC7985E5CD4C354" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConversableIncMember" xlink:label="loc_lpsn_ConversableIncMember_5D12A136C7BFD029B160985E5CD4B236" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9" xlink:to="loc_lpsn_ConversableIncMember_5D12A136C7BFD029B160985E5CD4B236" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AdvantageTecIncMember" xlink:label="loc_lpsn_AdvantageTecIncMember_CAFCE58A0FD933D40DD3985E5CD5A072" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionNameDomain_39D7D00B9DF66F9A3EDA985E5CD341F9" xlink:to="loc_lpsn_AdvantageTecIncMember_CAFCE58A0FD933D40DD3985E5CD5A072" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A8F409C995A6C3A7AA9A985E5CD5DF5C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A8F409C995A6C3A7AA9A985E5CD5DF5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_42580E18868B5C7BDF7B985E5CD572A7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A8F409C995A6C3A7AA9A985E5CD5DF5C" xlink:to="loc_us-gaap_NetIncomeLoss_42580E18868B5C7BDF7B985E5CD572A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A8F409C995A6C3A7AA9A985E5CD5DF5C" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_62B0E0BC437CC96BED00985E5CD678BE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_ShareBasedCompensation_62B0E0BC437CC96BED00985E5CD678BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_6AEFDD85D3827EC15461985E5CD6C259" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_6AEFDD85D3827EC15461985E5CD6C259" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TenantAllowanceAmortizationLessee" xlink:label="loc_lpsn_TenantAllowanceAmortizationLessee_ADE51EFC2C2B6D0F2A72985E5CD6D116" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_lpsn_TenantAllowanceAmortizationLessee_ADE51EFC2C2B6D0F2A72985E5CD6D116" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_6E3409BDA737042E9CE8985E5CD657F2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_6E3409BDA737042E9CE8985E5CD657F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_232A988304BECFBA1882985E5CD6BE16" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_232A988304BECFBA1882985E5CD6BE16" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfDebtDiscountPremium" xlink:label="loc_us-gaap_AmortizationOfDebtDiscountPremium_FC85648A1DE19CC40B8E985E5CD718D0" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_AmortizationOfDebtDiscountPremium_FC85648A1DE19CC40B8E985E5CD718D0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_7FD3AD9B323004B266AF985E5CD77334" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_7FD3AD9B323004B266AF985E5CD77334" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_042A79E36ADD465AA742985E5CD72006" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_042A79E36ADD465AA742985E5CD72006" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_8C2F39A05B773D6EE685985E5CD7C8F8" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_8C2F39A05B773D6EE685985E5CD7C8F8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_F3C0B6BDDF889469587D985E5CD63A2A" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_642297E7C060D33F4753985E5CD822BF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_642297E7C060D33F4753985E5CD822BF" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_IncreaseDecreaseInPrepaidExpenseAndOtherCurrentAssets" xlink:label="loc_lpsn_IncreaseDecreaseInPrepaidExpenseAndOtherCurrentAssets_D1026E6C005A8D6A6059985E5CD88339" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_lpsn_IncreaseDecreaseInPrepaidExpenseAndOtherCurrentAssets_D1026E6C005A8D6A6059985E5CD88339" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerAsset" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerAsset_E33BDC39C33DDB0FC765985E5CD8C6D6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_us-gaap_IncreaseDecreaseInContractWithCustomerAsset_E33BDC39C33DDB0FC765985E5CD8C6D6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_86F82E4AFEF148DD4C12985E5CD82DB6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_86F82E4AFEF148DD4C12985E5CD82DB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_40719025790F22FDB05E985E5CD8D31A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_40719025790F22FDB05E985E5CD8D31A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_2EBE2377F88B52BBA972985E5CD9ED64" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_2EBE2377F88B52BBA972985E5CD9ED64" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerLiability" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_3C4D4AB5ED35046C5834985E5CD97626" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_3C4D4AB5ED35046C5834985E5CD97626" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_IncreaseDecreaseInOperatingLeaseLiability" xlink:label="loc_lpsn_IncreaseDecreaseInOperatingLeaseLiability_6C38F0554DE8597DC004985E5CD9976B" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_lpsn_IncreaseDecreaseInOperatingLeaseLiability_6C38F0554DE8597DC004985E5CD9976B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_EF19FC9C2BD4FAD16B7D985E5CD9A1CB" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_EFEEB039EA486B3CDB12985E5CD78143" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherOperatingLiabilities_EF19FC9C2BD4FAD16B7D985E5CD9A1CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_DDCBD39C24E48E0FD916985E5CD9A85F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_A8F409C995A6C3A7AA9A985E5CD5DF5C" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_DDCBD39C24E48E0FD916985E5CD9A85F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_040B5A92AD6C1386836C985E5CD9EB90" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_040B5A92AD6C1386836C985E5CD9EB90" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsToAcquireProductiveAssets" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_012CFF958A52B2E5F6A4985E5CDA92AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_040B5A92AD6C1386836C985E5CD9EB90" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_012CFF958A52B2E5F6A4985E5CDA92AB" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_PaymentsToAcquireOtherIntangibleAssets" xlink:label="loc_lpsn_PaymentsToAcquireOtherIntangibleAssets_C4B00926F325406F971C985E5CDA5AC5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_040B5A92AD6C1386836C985E5CD9EB90" xlink:to="loc_lpsn_PaymentsToAcquireOtherIntangibleAssets_C4B00926F325406F971C985E5CDA5AC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInRestrictedCash" xlink:label="loc_us-gaap_IncreaseDecreaseInRestrictedCash_C1CB335C2809F722BB53985E5CDA3E5C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_040B5A92AD6C1386836C985E5CD9EB90" xlink:to="loc_us-gaap_IncreaseDecreaseInRestrictedCash_C1CB335C2809F722BB53985E5CDA3E5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_D2426217496D75128638985E5CDAD184" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_040B5A92AD6C1386836C985E5CD9EB90" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_D2426217496D75128638985E5CDAD184" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_3111369713D72CDDE4D5985E5CDA5E28" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_3111369713D72CDDE4D5985E5CDA5E28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_1E8C642CFBC1E44EC645985E5CDBAD1D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_1E8C642CFBC1E44EC645985E5CDBAD1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromConvertibleDebt" xlink:label="loc_us-gaap_ProceedsFromConvertibleDebt_D7117F204C3F1A1F6E2B985E5CDB5BEA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:to="loc_us-gaap_ProceedsFromConvertibleDebt_D7117F204C3F1A1F6E2B985E5CDB5BEA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsOfDebtIssuanceCosts" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_B3EA2118487832EABE70985E5CDB6EA9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_B3EA2118487832EABE70985E5CDB6EA9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" xlink:label="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_FCDA56DFFF68A21B2744985E5CDC1D0F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:to="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_FCDA56DFFF68A21B2744985E5CDC1D0F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsForDerivativeInstrumentFinancingActivities" xlink:label="loc_us-gaap_PaymentsForDerivativeInstrumentFinancingActivities_D62897DC70DB9BB97737985E5CDCCCC9" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:to="loc_us-gaap_PaymentsForDerivativeInstrumentFinancingActivities_D62897DC70DB9BB97737985E5CDCCCC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_5B3FD6AAD93CA9277E16985E5CDC6CEA" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_0FC64BD9D404214ACE09985E5CDAEA71" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_5B3FD6AAD93CA9277E16985E5CDC6CEA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_AC4D831919E593EF5085985E5CDC7E28" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_AC4D831919E593EF5085985E5CDC7E28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_613AE3CACE0DB5FEF2DF985E5CDCDA7C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_613AE3CACE0DB5FEF2DF985E5CDCDA7C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_58860EAF830C3AAC58B0985E5CDD821B" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_58860EAF830C3AAC58B0985E5CDD821B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_942CDC9A634F6144AC70985E5CDD500C" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_SupplementalCashFlowInformationAbstract_942CDC9A634F6144AC70985E5CDD500C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_D8378A0602CD58619E94985E5CDD9BFE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_942CDC9A634F6144AC70985E5CDD500C" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_D8378A0602CD58619E94985E5CDD9BFE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_4C40A306DDF56A84B493985E5CD5E705" xlink:to="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalExpendituresIncurredButNotYetPaid" xlink:label="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_2734F3FAEAA574A6E883985E5CDEC142" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:to="loc_us-gaap_CapitalExpendituresIncurredButNotYetPaid_2734F3FAEAA574A6E883985E5CDEC142" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_CapitalExpendituresPaidByLandlord" xlink:label="loc_lpsn_CapitalExpendituresPaidByLandlord_66299E365C57D7E178CC985E5CDEEB88" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:to="loc_lpsn_CapitalExpendituresPaidByLandlord_66299E365C57D7E178CC985E5CDEEB88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_04AAB5534FCDEC68858D985E5CDEC4DB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:to="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_04AAB5534FCDEC68858D985E5CDEC4DB" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_OperatingLeaseLiabilitySupplementalCashFlow" xlink:label="loc_lpsn_OperatingLeaseLiabilitySupplementalCashFlow_8FE1849B7E8DDB7AACAD985E5CDE9746" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:to="loc_lpsn_OperatingLeaseLiabilitySupplementalCashFlow_8FE1849B7E8DDB7AACAD985E5CDE9746" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherSignificantNoncashTransactionValueOfConsiderationGiven1" xlink:label="loc_us-gaap_OtherSignificantNoncashTransactionValueOfConsiderationGiven1_2B468AEC71C69942E00F985E5CDF719B" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:to="loc_us-gaap_OtherSignificantNoncashTransactionValueOfConsiderationGiven1_2B468AEC71C69942E00F985E5CDF719B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationSharesIssued1" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationSharesIssued1_CCF12D7BBD78046ED5CC985E5CDF8596" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:to="loc_us-gaap_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationSharesIssued1_CCF12D7BBD78046ED5CC985E5CDF8596" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsideration" xlink:label="loc_lpsn_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsideration_7E082801B5C6B357691F985E5CDFD88F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_3CBB627201E9418FA318985E5CDE40D5" xlink:to="loc_lpsn_BusinessCombinationContingentConsiderationArrangementsChangeinAmountofContingentConsideration_7E082801B5C6B357691F985E5CDFD88F" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConsolidatedStatementsOfComprehensiveLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConsolidatedStatementsOfOperations" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_1CDFE99D469B88B01C636DEF17D485C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_StatementTable_1CDFE99D469B88B01C636DEF17D485C5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_D0CC633806ACB90E3E0C6DEF17D4FC76" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1CDFE99D469B88B01C636DEF17D485C5" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_D0CC633806ACB90E3E0C6DEF17D4FC76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_5D68AA6D801907035E846DEF17D5246D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_D0CC633806ACB90E3E0C6DEF17D4FC76" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_5D68AA6D801907035E846DEF17D5246D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_5D68AA6D801907035E846DEF17D5246D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_D0CC633806ACB90E3E0C6DEF17D4FC76" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_5D68AA6D801907035E846DEF17D5246D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_C4425FC562BCC22B8EA66DEF17D56DA3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_5D68AA6D801907035E846DEF17D5246D" xlink:to="loc_us-gaap_CostOfSalesMember_C4425FC562BCC22B8EA66DEF17D56DA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_AFD38D8E29A41E6140DE6DEF17D52FE0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_5D68AA6D801907035E846DEF17D5246D" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_AFD38D8E29A41E6140DE6DEF17D52FE0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_7B85E2A15CC732D58ADF6DEF17D59323" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_5D68AA6D801907035E846DEF17D5246D" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_7B85E2A15CC732D58ADF6DEF17D59323" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_0437CC87C5709A4382596DEF17D5F9CC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_5D68AA6D801907035E846DEF17D5246D" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_0437CC87C5709A4382596DEF17D5F9CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_08147D4A935363E2912F6E21F1A0B0E6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_08147D4A935363E2912F6E21F1A0B0E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostsAndExpensesAbstract" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_64F76D14380363C56F5D6DEF17D62CE9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:to="loc_us-gaap_CostOfRevenue_64F76D14380363C56F5D6DEF17D62CE9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaap_SellingAndMarketingExpense_CBFCA92F69E7483CB6DF6DEF17D6F60C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:to="loc_us-gaap_SellingAndMarketingExpense_CBFCA92F69E7483CB6DF6DEF17D6F60C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_973CC3B2023D2775BB026DEF17D7B703" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_973CC3B2023D2775BB026DEF17D7B703" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_C91CFF15903A8FB6E37E6DEF17D7CC99" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_C91CFF15903A8FB6E37E6DEF17D7CC99" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_BE066ED8C6AEDD8818DF6DEF17D7467C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:to="loc_us-gaap_RestructuringCharges_BE066ED8C6AEDD8818DF6DEF17D7467C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AmortizationNonproduction" xlink:label="loc_lpsn_AmortizationNonproduction_8D89762BE42A8362EB156E199076CC81" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:to="loc_lpsn_AmortizationNonproduction_8D89762BE42A8362EB156E199076CC81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostsAndExpenses" xlink:label="loc_us-gaap_CostsAndExpenses_57F9E05D13CFFC5B3DE76DEF17D72E2E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_AE227D8D0BFAED2ED2486DEF17D67187" xlink:to="loc_us-gaap_CostsAndExpenses_57F9E05D13CFFC5B3DE76DEF17D72E2E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_AD65BE9D0359195837D56DEF17D7FFB2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_OperatingIncomeLoss_AD65BE9D0359195837D56DEF17D7FFB2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseAbstract" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_773C55FD4B11EC6234726DEF17D8B119" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_773C55FD4B11EC6234726DEF17D8B119" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet" xlink:label="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_90AD59A0650A684F1F086DEF17D82D46" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_773C55FD4B11EC6234726DEF17D8B119" xlink:to="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_90AD59A0650A684F1F086DEF17D82D46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_F40B48C4B4C9487123106DEF17D8253A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_773C55FD4B11EC6234726DEF17D8B119" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_F40B48C4B4C9487123106DEF17D8253A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_B23ED1BACAE937A32E106DEF17D84431" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpenseAbstract_773C55FD4B11EC6234726DEF17D8B119" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_B23ED1BACAE937A32E106DEF17D84431" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_89E3D2C21894531B861B6DEF17D8E46D" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_89E3D2C21894531B861B6DEF17D8E46D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_B6752B92FA2EC503A07C6DEF17D9E006" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_B6752B92FA2EC503A07C6DEF17D9E006" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_8A651911664D5800C66E6DEF17D98A62" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_NetIncomeLoss_8A651911664D5800C66E6DEF17D98A62" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_71E6221CB58F55ADF4196DEF17D92C5F" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_EarningsPerShareAbstract_71E6221CB58F55ADF4196DEF17D92C5F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_B89E35EC71EF618102FE6DEF17D98C09" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_71E6221CB58F55ADF4196DEF17D92C5F" xlink:to="loc_us-gaap_EarningsPerShareBasic_B89E35EC71EF618102FE6DEF17D98C09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_406145B4F711104F146C6DEF17D9BCA3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_71E6221CB58F55ADF4196DEF17D92C5F" xlink:to="loc_us-gaap_EarningsPerShareDiluted_406145B4F711104F146C6DEF17D9BCA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract_660DD2CDC761801A22CD6DEF17D9C6DC" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract_660DD2CDC761801A22CD6DEF17D9C6DC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_32458DE71ED8730AEF7C6DEF17DA0364" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract_660DD2CDC761801A22CD6DEF17D9C6DC" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_32458DE71ED8730AEF7C6DEF17DA0364" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_218F78304A4EC64BB0CE6DEF17DAA8C1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedOtherDisclosuresAbstract_660DD2CDC761801A22CD6DEF17D9C6DC" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_218F78304A4EC64BB0CE6DEF17DAA8C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="loc_us-gaap_OperatingExpensesAbstract_A081A59871561FC2D43F6DEF17DA131E" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_93209C517190F23DADA76DEF17D6F02C" xlink:to="loc_us-gaap_OperatingExpensesAbstract_A081A59871561FC2D43F6DEF17DA131E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_0E95458287563222FBFE6DEF17DAB026" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_A081A59871561FC2D43F6DEF17DA131E" xlink:to="loc_us-gaap_ShareBasedCompensation_0E95458287563222FBFE6DEF17DAB026" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_2390E884F4D185DD10B76DEF17DBF025" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_A081A59871561FC2D43F6DEF17DA131E" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_2390E884F4D185DD10B76DEF17DBF025" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostOfGoodsAndServicesSoldAmortization" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSoldAmortization_40FF10E77852A0087F166DEF17DB2AFD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_A081A59871561FC2D43F6DEF17DA131E" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSoldAmortization_40FF10E77852A0087F166DEF17DB2AFD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConsolidatedStatementsOfStockholdersEquity" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_90534900C222D23AE3AD65DB11B4A45D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_A2A9711D66941973C80F65DB11B10972" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_90534900C222D23AE3AD65DB11B4A45D" xlink:to="loc_us-gaap_StatementTable_A2A9711D66941973C80F65DB11B10972" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_1FA077C8EC072B2CD86365DB11B272C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_A2A9711D66941973C80F65DB11B10972" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_1FA077C8EC072B2CD86365DB11B272C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_1FA077C8EC072B2CD86365DB11B272C3" xlink:to="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_1FA077C8EC072B2CD86365DB11B272C3" xlink:to="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_C2A4CF8A51A4AF42F4D965DB11B3653A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F" xlink:to="loc_us-gaap_CommonStockMember_C2A4CF8A51A4AF42F4D965DB11B3653A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_F66D126BBD5B367E201365DB11B3EE37" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F" xlink:to="loc_us-gaap_TreasuryStockMember_F66D126BBD5B367E201365DB11B3EE37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_FA30F7293333C25BCA7965DB11B312D2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_FA30F7293333C25BCA7965DB11B312D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_DF4BD8D9EB995E85B04A65DB11B4CA83" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F" xlink:to="loc_us-gaap_RetainedEarningsMember_DF4BD8D9EB995E85B04A65DB11B4CA83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_BD06BC671432D010709865DB11B4F8A0" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_DDC934DEC3A1663C90B965DB11B2C25F" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_BD06BC671432D010709865DB11B4F8A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_90534900C222D23AE3AD65DB11B4A45D" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_B929909FAA0C6C086C2065DB11B4B305" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_SharesOutstanding_B929909FAA0C6C086C2065DB11B4B305" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_0F6A931892AE54FB185765DB11B55EDD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockholdersEquity_0F6A931892AE54FB185765DB11B55EDD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_89E683103AF2451BC3CD65DB11B5BDA4" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_89E683103AF2451BC3CD65DB11B5BDA4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_403B319E31740E0D68A865DB11B59172" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_403B319E31740E0D68A865DB11B59172" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_C79E5997199EC2F920E565DB11B7F288" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_C79E5997199EC2F920E565DB11B7F288" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_18E7C4880AB7BFE9D90E65DB11B73A2D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_18E7C4880AB7BFE9D90E65DB11B73A2D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_FDCA6E500691281C5C7865DB11B7D03A" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_FDCA6E500691281C5C7865DB11B7D03A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_CD055A378C9757B780B265DB11B7E0F8" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_CD055A378C9757B780B265DB11B7E0F8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_A2433E2F538B8AB23CA765DB11B78A7A" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_A2433E2F538B8AB23CA765DB11B78A7A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_572A19CD61D2EDCBFE6D65DB11B791F0" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_572A19CD61D2EDCBFE6D65DB11B791F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_28EC6A55E7FE237EAD5B65DB11B8DC77" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_28EC6A55E7FE237EAD5B65DB11B8DC77" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1" xlink:label="loc_us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1_C2303AD7F4EA72AF66CE65DB11B8D7E9" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_CumulativeEffectOnRetainedEarningsNetOfTax1_C2303AD7F4EA72AF66CE65DB11B8D7E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_CC9110151D633D76BDBD65DB11B8527B" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_CC9110151D633D76BDBD65DB11B8527B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_158BDAF313EF0FE496B265DB11B885A7" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_158BDAF313EF0FE496B265DB11B885A7" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DebtConversionOptionsIssuedDuringPeriod" xlink:label="loc_lpsn_DebtConversionOptionsIssuedDuringPeriod_02626607118CEA14BF4865DB11B83645" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_lpsn_DebtConversionOptionsIssuedDuringPeriod_02626607118CEA14BF4865DB11B83645" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AdjustmentstoAdditionalPaidinCapitalDebtConversionOptionIssuanceCosts" xlink:label="loc_lpsn_AdjustmentstoAdditionalPaidinCapitalDebtConversionOptionIssuanceCosts_00065C839495211B510265DB11B854CB" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_lpsn_AdjustmentstoAdditionalPaidinCapitalDebtConversionOptionIssuanceCosts_00065C839495211B510265DB11B854CB" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AdjustmentstoAdditionalPaidinCapitalCappedCallOptionIssuanceCosts" xlink:label="loc_lpsn_AdjustmentstoAdditionalPaidinCapitalCappedCallOptionIssuanceCosts_1BA3B6169A83C52EF81765DB11B91F7A" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_lpsn_AdjustmentstoAdditionalPaidinCapitalCappedCallOptionIssuanceCosts_1BA3B6169A83C52EF81765DB11B91F7A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_B131065004B2846040FE65DB11B92E5D" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_NetIncomeLoss_B131065004B2846040FE65DB11B92E5D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_BFF2D791C793EF5588E665DB11B9BE5D" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_595E8462CCF6344BC99165DB11B4328C" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_BFF2D791C793EF5588E665DB11B9BE5D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConvertibleSeniorNotesAndCappedCallTransactions" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConvertibleSeniorNotesAndCappedCallTransactionsCarryingAmountAndInterestExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_38E4055D757242D260D2663FDA1B1457" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_20D36375587CC2515A4A663FDA1907CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_38E4055D757242D260D2663FDA1B1457" xlink:to="loc_us-gaap_DebtInstrumentTable_20D36375587CC2515A4A663FDA1907CC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_494B6760C29AC66C5857663FDA1A964B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_20D36375587CC2515A4A663FDA1907CC" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_494B6760C29AC66C5857663FDA1A964B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_C0D947EAA4BC8DBFC0EC663FDA1AD3D3_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_494B6760C29AC66C5857663FDA1A964B" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_C0D947EAA4BC8DBFC0EC663FDA1AD3D3_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_C0D947EAA4BC8DBFC0EC663FDA1AD3D3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_494B6760C29AC66C5857663FDA1A964B" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_C0D947EAA4BC8DBFC0EC663FDA1AD3D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConvertibleDebtMember" xlink:label="loc_us-gaap_ConvertibleDebtMember_388D544EA51E63A20E19663FDA1AD853" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_C0D947EAA4BC8DBFC0EC663FDA1AD3D3" xlink:to="loc_us-gaap_ConvertibleDebtMember_388D544EA51E63A20E19663FDA1AD853" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_C2B6767EADAA155CF515663FDA1A8F6F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_20D36375587CC2515A4A663FDA1907CC" xlink:to="loc_us-gaap_DebtInstrumentAxis_C2B6767EADAA155CF515663FDA1A8F6F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_B08A50F7CFFD92E16A4C663FDA1B99AF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_C2B6767EADAA155CF515663FDA1A8F6F" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_B08A50F7CFFD92E16A4C663FDA1B99AF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_B08A50F7CFFD92E16A4C663FDA1B99AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_C2B6767EADAA155CF515663FDA1A8F6F" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_B08A50F7CFFD92E16A4C663FDA1B99AF" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConvertibleSeniorNotesMember" xlink:label="loc_lpsn_ConvertibleSeniorNotesMember_24CC83E6658B1EC6C02E663FDA1BC5C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_B08A50F7CFFD92E16A4C663FDA1B99AF" xlink:to="loc_lpsn_ConvertibleSeniorNotesMember_24CC83E6658B1EC6C02E663FDA1BC5C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebtAbstract" xlink:label="loc_us-gaap_LongTermDebtAbstract_493EEDDC2353FA3E796A663FDA1B82D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_38E4055D757242D260D2663FDA1B1457" xlink:to="loc_us-gaap_LongTermDebtAbstract_493EEDDC2353FA3E796A663FDA1B82D0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_03C8C1EA85A6BA12E2AF663FDA1BEBD6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_493EEDDC2353FA3E796A663FDA1B82D0" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_03C8C1EA85A6BA12E2AF663FDA1BEBD6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscount" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscount_3B67F2FAF64E13DE465C663FDA1CC3D5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_493EEDDC2353FA3E796A663FDA1B82D0" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscount_3B67F2FAF64E13DE465C663FDA1CC3D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredFinanceCostsNet" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_0D16EE1B0409AD260B42663FDA1C4F30" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_493EEDDC2353FA3E796A663FDA1B82D0" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_0D16EE1B0409AD260B42663FDA1C4F30" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_1838F8BCF73199DA93E1663FDA1CA6CF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermDebtAbstract_493EEDDC2353FA3E796A663FDA1B82D0" xlink:to="loc_us-gaap_LongTermDebt_1838F8BCF73199DA93E1663FDA1CA6CF" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConvertibleDebtEquityComponentAbstract" xlink:label="loc_lpsn_ConvertibleDebtEquityComponentAbstract_061C89163AE656133497663FDA1C1011" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_38E4055D757242D260D2663FDA1B1457" xlink:to="loc_lpsn_ConvertibleDebtEquityComponentAbstract_061C89163AE656133497663FDA1C1011" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent" xlink:label="loc_us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent_2D8637CEFE52B7CB587A663FDA1C76ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ConvertibleDebtEquityComponentAbstract_061C89163AE656133497663FDA1C1011" xlink:to="loc_us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent_2D8637CEFE52B7CB587A663FDA1C76ED" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DeferredFinanceCostsAllocatedToEquityComponent" xlink:label="loc_lpsn_DeferredFinanceCostsAllocatedToEquityComponent_89DC3756B77932DBA0AA663FDA1DEEDB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ConvertibleDebtEquityComponentAbstract_061C89163AE656133497663FDA1C1011" xlink:to="loc_lpsn_DeferredFinanceCostsAllocatedToEquityComponent_89DC3756B77932DBA0AA663FDA1DEEDB" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DebtInstrumentConvertibleCarryingAmountOfEquityComponentNetOfIssuanceCosts" xlink:label="loc_lpsn_DebtInstrumentConvertibleCarryingAmountOfEquityComponentNetOfIssuanceCosts_EA6DA20507337647A389663FDA1D9FD9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ConvertibleDebtEquityComponentAbstract_061C89163AE656133497663FDA1C1011" xlink:to="loc_lpsn_DebtInstrumentConvertibleCarryingAmountOfEquityComponentNetOfIssuanceCosts_EA6DA20507337647A389663FDA1D9FD9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpenseDebtAbstract" xlink:label="loc_us-gaap_InterestExpenseDebtAbstract_71F9F5AA6DD8184A33DE663FDA1DC2EC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_38E4055D757242D260D2663FDA1B1457" xlink:to="loc_us-gaap_InterestExpenseDebtAbstract_71F9F5AA6DD8184A33DE663FDA1DC2EC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpenseDebtExcludingAmortization" xlink:label="loc_us-gaap_InterestExpenseDebtExcludingAmortization_A9BE84A370AC5C0ECE36663FDA1DBA83" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseDebtAbstract_71F9F5AA6DD8184A33DE663FDA1DC2EC" xlink:to="loc_us-gaap_InterestExpenseDebtExcludingAmortization_A9BE84A370AC5C0ECE36663FDA1DBA83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_2B00AEFAFFDE866C0645663FDA1DA72C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseDebtAbstract_71F9F5AA6DD8184A33DE663FDA1DC2EC" xlink:to="loc_us-gaap_AmortizationOfFinancingCosts_2B00AEFAFFDE866C0645663FDA1DA72C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfDebtDiscountPremium" xlink:label="loc_us-gaap_AmortizationOfDebtDiscountPremium_A2707A8D387B1E895B06663FDA1DE9E1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseDebtAbstract_71F9F5AA6DD8184A33DE663FDA1DC2EC" xlink:to="loc_us-gaap_AmortizationOfDebtDiscountPremium_A2707A8D387B1E895B06663FDA1DE9E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpenseDebt" xlink:label="loc_us-gaap_InterestExpenseDebt_98CCC629745FEE122867663FDA1E6E06" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InterestExpenseDebtAbstract_71F9F5AA6DD8184A33DE663FDA1DC2EC" xlink:to="loc_us-gaap_InterestExpenseDebt_98CCC629745FEE122867663FDA1E6E06" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConvertibleSeniorNotesAndCappedCallTransactionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_4DDEF9EE07490CEAE544663FDA246A05" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentTable_4DDEF9EE07490CEAE544663FDA246A05" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_9CCBCAFD84F4F4817E44663FDA253337" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4DDEF9EE07490CEAE544663FDA246A05" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_9CCBCAFD84F4F4817E44663FDA253337" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_C3D6225D1D9F88E9797A663FDA25F733_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_9CCBCAFD84F4F4817E44663FDA253337" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_C3D6225D1D9F88E9797A663FDA25F733_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_C3D6225D1D9F88E9797A663FDA25F733" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_9CCBCAFD84F4F4817E44663FDA253337" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_C3D6225D1D9F88E9797A663FDA25F733" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherExpenseMember" xlink:label="loc_us-gaap_OtherExpenseMember_C1CA96FB5270465CB8C1663FDA250E20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_C3D6225D1D9F88E9797A663FDA25F733" xlink:to="loc_us-gaap_OtherExpenseMember_C1CA96FB5270465CB8C1663FDA250E20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_B7B9083ECF5982FA36BF663FDA25D128" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4DDEF9EE07490CEAE544663FDA246A05" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_B7B9083ECF5982FA36BF663FDA25D128" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_0A1C7C93D3EA565C895F663FDA26CFCC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_B7B9083ECF5982FA36BF663FDA25D128" xlink:to="loc_us-gaap_EquityComponentDomain_0A1C7C93D3EA565C895F663FDA26CFCC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_0A1C7C93D3EA565C895F663FDA26CFCC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_B7B9083ECF5982FA36BF663FDA25D128" xlink:to="loc_us-gaap_EquityComponentDomain_0A1C7C93D3EA565C895F663FDA26CFCC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_213D143E119CD61B60F6663FDA26A0A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0A1C7C93D3EA565C895F663FDA26CFCC" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_213D143E119CD61B60F6663FDA26A0A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_E269F4C33E1398D27CAE663FDA26BE32" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4DDEF9EE07490CEAE544663FDA246A05" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_E269F4C33E1398D27CAE663FDA26BE32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8B766437779F65A16356663FDA26908F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_E269F4C33E1398D27CAE663FDA26BE32" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8B766437779F65A16356663FDA26908F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8B766437779F65A16356663FDA26908F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_E269F4C33E1398D27CAE663FDA26BE32" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8B766437779F65A16356663FDA26908F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConvertibleDebtMember" xlink:label="loc_us-gaap_ConvertibleDebtMember_9CFDF14065305D20E240663FDA27D280" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8B766437779F65A16356663FDA26908F" xlink:to="loc_us-gaap_ConvertibleDebtMember_9CFDF14065305D20E240663FDA27D280" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_7D7BEAB5F98CCF234D2F663FDA277DDA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4DDEF9EE07490CEAE544663FDA246A05" xlink:to="loc_us-gaap_DebtInstrumentAxis_7D7BEAB5F98CCF234D2F663FDA277DDA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_E761A3C09989688E9D4F663FDA27C866_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7D7BEAB5F98CCF234D2F663FDA277DDA" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_E761A3C09989688E9D4F663FDA27C866_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_E761A3C09989688E9D4F663FDA27C866" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7D7BEAB5F98CCF234D2F663FDA277DDA" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_E761A3C09989688E9D4F663FDA27C866" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConvertibleSeniorNotesMember" xlink:label="loc_lpsn_ConvertibleSeniorNotesMember_5C13C1D63DF93095AB6F663FDA27A3F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_E761A3C09989688E9D4F663FDA27C866" xlink:to="loc_lpsn_ConvertibleSeniorNotesMember_5C13C1D63DF93095AB6F663FDA27A3F3" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_CappedCallsMember" xlink:label="loc_lpsn_CappedCallsMember_746FAA1D6DB80167C47B663FDA28E37B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_E761A3C09989688E9D4F663FDA27C866" xlink:to="loc_lpsn_CappedCallsMember_746FAA1D6DB80167C47B663FDA28E37B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_121E8C95F5D73904D7A6663FDA28CB48" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_121E8C95F5D73904D7A6663FDA28CB48" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_9AB3D415D6940DCF3166663FDA2820FA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_9AB3D415D6940DCF3166663FDA2820FA" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AggregatePrincipalFromExerciseInFullOfOverAllotmentOptions" xlink:label="loc_lpsn_AggregatePrincipalFromExerciseInFullOfOverAllotmentOptions_8624F1C28921EFB1550F663FDA288D61" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_AggregatePrincipalFromExerciseInFullOfOverAllotmentOptions_8624F1C28921EFB1550F663FDA288D61" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromDebtNetOfIssuanceCosts" xlink:label="loc_us-gaap_ProceedsFromDebtNetOfIssuanceCosts_733366F4B437506C9079663FDA289BC3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_ProceedsFromDebtNetOfIssuanceCosts_733366F4B437506C9079663FDA289BC3" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DebtInstrumentUnitOfPrincipalForConversionAmount" xlink:label="loc_lpsn_DebtInstrumentUnitOfPrincipalForConversionAmount_D95318F09BAC38EF43CF663FDA299E33" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_DebtInstrumentUnitOfPrincipalForConversionAmount_D95318F09BAC38EF43CF663FDA299E33" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DebtInstrumentConvertibleNumberofEquityInstrumentsPer1000Principal" xlink:label="loc_lpsn_DebtInstrumentConvertibleNumberofEquityInstrumentsPer1000Principal_96B2E3BD766D1A3EF2A6663FDA29F026" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_DebtInstrumentConvertibleNumberofEquityInstrumentsPer1000Principal_96B2E3BD766D1A3EF2A6663FDA29F026" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_9049A8D202FB959190B4663FDA29C57E" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_9049A8D202FB959190B4663FDA29C57E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_FA8A10C5B2ED5956B86B663FDA293DC5" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_FA8A10C5B2ED5956B86B663FDA293DC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_7A2FF673D3D9B448AC81663FDA29749E" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_7A2FF673D3D9B448AC81663FDA29749E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentConvertibleThresholdTradingDays" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_07998A29573B608BE5AE663FDA29BC92" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_07998A29573B608BE5AE663FDA29BC92" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_B8F4503E1724107BF8DF663FDA2AF64E" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_B8F4503E1724107BF8DF663FDA2AF64E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_7ED8D1DD9E7D6458BA6B663FDA2AAB63" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_7ED8D1DD9E7D6458BA6B663FDA2AAB63" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DebtInstrumentConvertibleFiveDayPeriodThresholdOfProductOfSalePriceOfStockAndConversionRate" xlink:label="loc_lpsn_DebtInstrumentConvertibleFiveDayPeriodThresholdOfProductOfSalePriceOfStockAndConversionRate_C7D742179966A07CA179663FDA2A0EA3" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_DebtInstrumentConvertibleFiveDayPeriodThresholdOfProductOfSalePriceOfStockAndConversionRate_C7D742179966A07CA179663FDA2A0EA3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent" xlink:label="loc_us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent_B135C5788C9FCE7198A4663FDA2A16ED" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentConvertibleCarryingAmountOfTheEquityComponent_B135C5788C9FCE7198A4663FDA2A16ED" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DeferredFinanceCostsLiabilityAndEquityComponent" xlink:label="loc_lpsn_DeferredFinanceCostsLiabilityAndEquityComponent_306F1A7BC5EF05FFBC02663FDA2A952E" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_DeferredFinanceCostsLiabilityAndEquityComponent_306F1A7BC5EF05FFBC02663FDA2A952E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredFinanceCostsGross" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_67BB7903C04566DF2E45663FDA2A02C5" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_67BB7903C04566DF2E45663FDA2A02C5" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AdjustmentstoAdditionalPaidinCapitalDebtConversionOptionIssuanceCosts" xlink:label="loc_lpsn_AdjustmentstoAdditionalPaidinCapitalDebtConversionOptionIssuanceCosts_1EBDBA9173380C70C871663FDA2C76FF" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_AdjustmentstoAdditionalPaidinCapitalDebtConversionOptionIssuanceCosts_1EBDBA9173380C70C871663FDA2C76FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentConvertibleRemainingDiscountAmortizationPeriod1" xlink:label="loc_us-gaap_DebtInstrumentConvertibleRemainingDiscountAmortizationPeriod1_7D90AFDAF21AB99B658C663FDA2BA003" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentConvertibleRemainingDiscountAmortizationPeriod1_7D90AFDAF21AB99B658C663FDA2BA003" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_F37E8022AA1D23319039663FDA2BC3C7" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_F37E8022AA1D23319039663FDA2BC3C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpenseDebt" xlink:label="loc_us-gaap_InterestExpenseDebt_71E0CF0FE31CE75A560C663FDA2B5AAF" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_us-gaap_InterestExpenseDebt_71E0CF0FE31CE75A560C663FDA2B5AAF" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_CappedCallsInitialOptionStrikePrice" xlink:label="loc_lpsn_CappedCallsInitialOptionStrikePrice_FC01C2F4901AA11185A8663FDA2BB77B" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_CappedCallsInitialOptionStrikePrice_FC01C2F4901AA11185A8663FDA2BB77B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_CappedCallsInitialCapPrice" xlink:label="loc_lpsn_CappedCallsInitialCapPrice_0C7B1FBDB75A9B1CAAAB663FDA2BBE53" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_CappedCallsInitialCapPrice_0C7B1FBDB75A9B1CAAAB663FDA2BBE53" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_NumberOfSharesOfCommonStockCoveredByCappedCalls" xlink:label="loc_lpsn_NumberOfSharesOfCommonStockCoveredByCappedCalls_7FFE2C1D4C07E74636A9663FDA2B837D" xlink:type="locator" />
    <link:definitionArc order="23" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_NumberOfSharesOfCommonStockCoveredByCappedCalls_7FFE2C1D4C07E74636A9663FDA2B837D" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AdjustmentstoAdditionalPaidinCapitalCappedCallOptionIssuanceCosts" xlink:label="loc_lpsn_AdjustmentstoAdditionalPaidinCapitalCappedCallOptionIssuanceCosts_956A6078E940E9FE32E2663FDA2B4281" xlink:type="locator" />
    <link:definitionArc order="24" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_519CB16E2D578D4ADC48663FDA28A49F" xlink:to="loc_lpsn_AdjustmentstoAdditionalPaidinCapitalCappedCallOptionIssuanceCosts_956A6078E940E9FE32E2663FDA2B4281" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/ConvertibleSeniorNotesAndCappedCallTransactionsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CoverPage" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesAccountsReceivableDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDeferredRevenueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_DC7584C8D69DBCCE09198AA0CE590502" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_744288F70B4AA907238E8AA0CE580EF9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_DC7584C8D69DBCCE09198AA0CE590502" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_744288F70B4AA907238E8AA0CE580EF9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_A766A4BE354F6F5F51F48AA0CE581C37" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_744288F70B4AA907238E8AA0CE580EF9" xlink:to="loc_srt_ProductOrServiceAxis_A766A4BE354F6F5F51F48AA0CE581C37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_05BA302FCB2DFF70D2228AA0CE59E298_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_A766A4BE354F6F5F51F48AA0CE581C37" xlink:to="loc_srt_ProductsAndServicesDomain_05BA302FCB2DFF70D2228AA0CE59E298_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_05BA302FCB2DFF70D2228AA0CE59E298" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_A766A4BE354F6F5F51F48AA0CE581C37" xlink:to="loc_srt_ProductsAndServicesDomain_05BA302FCB2DFF70D2228AA0CE59E298" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_HostedServicesBusinessMember" xlink:label="loc_lpsn_HostedServicesBusinessMember_1CA847161BA02CF147CE8AA0CE592A25" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_05BA302FCB2DFF70D2228AA0CE59E298" xlink:to="loc_lpsn_HostedServicesBusinessMember_1CA847161BA02CF147CE8AA0CE592A25" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_HostedServicesConsumerMember" xlink:label="loc_lpsn_HostedServicesConsumerMember_C7E66EB5A69B6DA550058ABAC5074540" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_05BA302FCB2DFF70D2228AA0CE59E298" xlink:to="loc_lpsn_HostedServicesConsumerMember_C7E66EB5A69B6DA550058ABAC5074540" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ProfessionalServicesMember" xlink:label="loc_lpsn_ProfessionalServicesMember_FB2A3D38010054E33A948AA0CE5943C7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_05BA302FCB2DFF70D2228AA0CE59E298" xlink:to="loc_lpsn_ProfessionalServicesMember_FB2A3D38010054E33A948AA0CE5943C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_6CD554F636902D48E2DB8AA0CE5A7734" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_DC7584C8D69DBCCE09198AA0CE590502" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_6CD554F636902D48E2DB8AA0CE5A7734" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_50089AD7923D4BF81E528AA0CE5A0C8B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_DC7584C8D69DBCCE09198AA0CE590502" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_50089AD7923D4BF81E528AA0CE5A0C8B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesReceivablesAndDeferredRevenueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_0B0A9370378A81B109EA985E5C7C2BA9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_E0C05BA92A5C1735BC9A985E5C7AB4C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_0B0A9370378A81B109EA985E5C7C2BA9" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_E0C05BA92A5C1735BC9A985E5C7AB4C5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis" xlink:label="loc_us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis_933F980597BDEB6AF119985E5C7BCBF6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_E0C05BA92A5C1735BC9A985E5C7AB4C5" xlink:to="loc_us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis_933F980597BDEB6AF119985E5C7BCBF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReceivablesBillingStatusDomain" xlink:label="loc_us-gaap_ReceivablesBillingStatusDomain_9DAE0AFE49C9CE087EEC985E5C7B0CFC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis_933F980597BDEB6AF119985E5C7BCBF6" xlink:to="loc_us-gaap_ReceivablesBillingStatusDomain_9DAE0AFE49C9CE087EEC985E5C7B0CFC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReceivablesBillingStatusDomain" xlink:label="loc_us-gaap_ReceivablesBillingStatusDomain_9DAE0AFE49C9CE087EEC985E5C7B0CFC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AccountsNotesLoansAndFinancingReceivablesByBillingStatusTypeAxis_933F980597BDEB6AF119985E5C7BCBF6" xlink:to="loc_us-gaap_ReceivablesBillingStatusDomain_9DAE0AFE49C9CE087EEC985E5C7B0CFC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BilledRevenuesMember" xlink:label="loc_us-gaap_BilledRevenuesMember_42D89D4446742E9A8CE0985E5C7B0818" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivablesBillingStatusDomain_9DAE0AFE49C9CE087EEC985E5C7B0CFC" xlink:to="loc_us-gaap_BilledRevenuesMember_42D89D4446742E9A8CE0985E5C7B0818" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnbilledRevenuesMember" xlink:label="loc_us-gaap_UnbilledRevenuesMember_1E640398F7E5A5BCB7D6985E5C7BDF4A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReceivablesBillingStatusDomain_9DAE0AFE49C9CE087EEC985E5C7B0CFC" xlink:to="loc_us-gaap_UnbilledRevenuesMember_1E640398F7E5A5BCB7D6985E5C7BDF4A" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ContractBalancesRollForward" xlink:label="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_0B0A9370378A81B109EA985E5C7C2BA9" xlink:to="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_AB9DB33A89ECF12EFC9D985E5C7CE570" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_AB9DB33A89ECF12EFC9D985E5C7CE570" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_IncreaseDecreaseInBilledReceivables" xlink:label="loc_lpsn_IncreaseDecreaseInBilledReceivables_CAE7741D007B8F625A8F985E5C7C5E20" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_lpsn_IncreaseDecreaseInBilledReceivables_CAE7741D007B8F625A8F985E5C7C5E20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInUnbilledReceivables" xlink:label="loc_us-gaap_IncreaseDecreaseInUnbilledReceivables_A3470C25AA87F24387EC985E5C7CBEF8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_us-gaap_IncreaseDecreaseInUnbilledReceivables_A3470C25AA87F24387EC985E5C7CBEF8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalizedContractCostNet" xlink:label="loc_us-gaap_CapitalizedContractCostNet_2F9A088624ED540AB8B9985E5C7DD52A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_us-gaap_CapitalizedContractCostNet_2F9A088624ED540AB8B9985E5C7DD52A" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_IncreaseDecreaseInCapitalizedContractCost" xlink:label="loc_lpsn_IncreaseDecreaseInCapitalizedContractCost_93F13EBAE4A364915962985E5C7D7848" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_lpsn_IncreaseDecreaseInCapitalizedContractCost_93F13EBAE4A364915962985E5C7D7848" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_F9B348D4C5522ACB4D4F985E5C7DADD4" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_F9B348D4C5522ACB4D4F985E5C7DADD4" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_IncreaseDecreaseinDeferredRevenueCurrent" xlink:label="loc_lpsn_IncreaseDecreaseinDeferredRevenueCurrent_1C36ED605E9004D703B1985E5C7DEA14" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_lpsn_IncreaseDecreaseinDeferredRevenueCurrent_1C36ED605E9004D703B1985E5C7DEA14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_08D308A875E6C7C02C60985E5C7E1D3D" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_08D308A875E6C7C02C60985E5C7E1D3D" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_IncreaseDecreaseinDeferredRevenueNoncurrent" xlink:label="loc_lpsn_IncreaseDecreaseinDeferredRevenueNoncurrent_C0A7446721EB1B047B7A985E5C7E0D14" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ContractBalancesRollForward_647638BAF02CE4BEEF6F985E5C7C47FB" xlink:to="loc_lpsn_IncreaseDecreaseinDeferredRevenueNoncurrent_C0A7446721EB1B047B7A985E5C7E0D14" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDisaggregationOfRevenueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_26AF7DAAD691A1C4FE158AA0CE55B2A3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_039522F91CFD65213EA18AA0CE54D038" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_26AF7DAAD691A1C4FE158AA0CE55B2A3" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_039522F91CFD65213EA18AA0CE54D038" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_AA117541EDCED688D0B18AA0CE541C51" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_039522F91CFD65213EA18AA0CE54D038" xlink:to="loc_srt_ProductOrServiceAxis_AA117541EDCED688D0B18AA0CE541C51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_78AB9636CE4E9A3526BA8AA0CE540233_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_AA117541EDCED688D0B18AA0CE541C51" xlink:to="loc_srt_ProductsAndServicesDomain_78AB9636CE4E9A3526BA8AA0CE540233_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_78AB9636CE4E9A3526BA8AA0CE540233" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_AA117541EDCED688D0B18AA0CE541C51" xlink:to="loc_srt_ProductsAndServicesDomain_78AB9636CE4E9A3526BA8AA0CE540233" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_HostedServicesBusinessMember" xlink:label="loc_lpsn_HostedServicesBusinessMember_37D7376308EA1B2C5D768AA0CE5525D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_78AB9636CE4E9A3526BA8AA0CE540233" xlink:to="loc_lpsn_HostedServicesBusinessMember_37D7376308EA1B2C5D768AA0CE5525D0" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_HostedServicesConsumerMember" xlink:label="loc_lpsn_HostedServicesConsumerMember_69BB2501692459E01F688AA0CE5574BD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_78AB9636CE4E9A3526BA8AA0CE540233" xlink:to="loc_lpsn_HostedServicesConsumerMember_69BB2501692459E01F688AA0CE5574BD" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ProfessionalServicesMember" xlink:label="loc_lpsn_ProfessionalServicesMember_99AA4B524C0538FC994A8AA0CE55E569" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_78AB9636CE4E9A3526BA8AA0CE540233" xlink:to="loc_lpsn_ProfessionalServicesMember_99AA4B524C0538FC994A8AA0CE55E569" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_B4EE2D10396ED48F58258AA0CE55D0F9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_26AF7DAAD691A1C4FE158AA0CE55B2A3" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_B4EE2D10396ED48F58258AA0CE55D0F9" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems" xlink:label="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:type="locator" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable" xlink:label="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable_D7DB7146996DEECC3991985E5CA1BB62" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable_D7DB7146996DEECC3991985E5CA1BB62" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_05BDF60562D264826E9C985E5CA1CF41" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable_D7DB7146996DEECC3991985E5CA1BB62" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_05BDF60562D264826E9C985E5CA1CF41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_250A854C8E6B28EE4C75985E5CA16AD6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_05BDF60562D264826E9C985E5CA1CF41" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_250A854C8E6B28EE4C75985E5CA16AD6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_250A854C8E6B28EE4C75985E5CA16AD6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_05BDF60562D264826E9C985E5CA1CF41" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_250A854C8E6B28EE4C75985E5CA16AD6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_21B9DAC81A79D6FAC5B3985E5CA2AF9C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_250A854C8E6B28EE4C75985E5CA16AD6" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_21B9DAC81A79D6FAC5B3985E5CA2AF9C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_37B62564A8A8B32DC694985E5CA2C65B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable_D7DB7146996DEECC3991985E5CA1BB62" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_37B62564A8A8B32DC694985E5CA2C65B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4C78DDE42CAC873425DA985E5CA2C5B2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_37B62564A8A8B32DC694985E5CA2C65B" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4C78DDE42CAC873425DA985E5CA2C5B2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4C78DDE42CAC873425DA985E5CA2C5B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_37B62564A8A8B32DC694985E5CA2C65B" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4C78DDE42CAC873425DA985E5CA2C5B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaap_AccountsReceivableMember_D5196A650570F24CCA82985E5CA2A454" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_4C78DDE42CAC873425DA985E5CA2C5B2" xlink:to="loc_us-gaap_AccountsReceivableMember_D5196A650570F24CCA82985E5CA2A454" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MajorCustomersAxis" xlink:label="loc_srt_MajorCustomersAxis_2FE82EA741C4CFAC78B0985E5CA36A2C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable_D7DB7146996DEECC3991985E5CA1BB62" xlink:to="loc_srt_MajorCustomersAxis_2FE82EA741C4CFAC78B0985E5CA36A2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_8F97AD66199337B48123985E5CA3095C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_2FE82EA741C4CFAC78B0985E5CA36A2C" xlink:to="loc_srt_NameOfMajorCustomerDomain_8F97AD66199337B48123985E5CA3095C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_8F97AD66199337B48123985E5CA3095C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_2FE82EA741C4CFAC78B0985E5CA36A2C" xlink:to="loc_srt_NameOfMajorCustomerDomain_8F97AD66199337B48123985E5CA3095C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TwoCustomersMember" xlink:label="loc_lpsn_TwoCustomersMember_7E5335290D245FA76262985E5CA49117" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_8F97AD66199337B48123985E5CA3095C" xlink:to="loc_lpsn_TwoCustomersMember_7E5335290D245FA76262985E5CA49117" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_20195EA3D9FC541AEB05985E5CA4F8E3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable_D7DB7146996DEECC3991985E5CA1BB62" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_20195EA3D9FC541AEB05985E5CA4F8E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_7A6EF5D0253C48C098E5985E5CA43B35_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_20195EA3D9FC541AEB05985E5CA4F8E3" xlink:to="loc_us-gaap_TypeOfAdoptionMember_7A6EF5D0253C48C098E5985E5CA43B35_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfAdoptionMember" xlink:label="loc_us-gaap_TypeOfAdoptionMember_7A6EF5D0253C48C098E5985E5CA43B35" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_20195EA3D9FC541AEB05985E5CA4F8E3" xlink:to="loc_us-gaap_TypeOfAdoptionMember_7A6EF5D0253C48C098E5985E5CA43B35" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountingStandardsUpdate201602Member" xlink:label="loc_us-gaap_AccountingStandardsUpdate201602Member_2B2BD15AA3FBFEDBBD83985E5CA4E863" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_7A6EF5D0253C48C098E5985E5CA43B35" xlink:to="loc_us-gaap_AccountingStandardsUpdate201602Member_2B2BD15AA3FBFEDBBD83985E5CA4E863" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_CD03A7EC76D9398A5473985E5CA5EBB4" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable_D7DB7146996DEECC3991985E5CA1BB62" xlink:to="loc_srt_RangeAxis_CD03A7EC76D9398A5473985E5CA5EBB4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_FF2FA6401315BE85CDDB985E5CA55C20_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_CD03A7EC76D9398A5473985E5CA5EBB4" xlink:to="loc_srt_RangeMember_FF2FA6401315BE85CDDB985E5CA55C20_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_FF2FA6401315BE85CDDB985E5CA55C20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_CD03A7EC76D9398A5473985E5CA5EBB4" xlink:to="loc_srt_RangeMember_FF2FA6401315BE85CDDB985E5CA55C20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_4F4534FE260F449E2001985E5CA591AA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_FF2FA6401315BE85CDDB985E5CA55C20" xlink:to="loc_srt_MinimumMember_4F4534FE260F449E2001985E5CA591AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_4E99F9BCB7F61DF34611985E5CA5C9F7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_FF2FA6401315BE85CDDB985E5CA55C20" xlink:to="loc_srt_MaximumMember_4E99F9BCB7F61DF34611985E5CA5C9F7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_D25E0E8F95D48F298914985E5CA6260C" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesTable_D7DB7146996DEECC3991985E5CA1BB62" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_D25E0E8F95D48F298914985E5CA6260C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0A9B8423BF4911D37C17985E5CA6CCFB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_D25E0E8F95D48F298914985E5CA6260C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0A9B8423BF4911D37C17985E5CA6CCFB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0A9B8423BF4911D37C17985E5CA6CCFB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_D25E0E8F95D48F298914985E5CA6260C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0A9B8423BF4911D37C17985E5CA6CCFB" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ComputerEquipmentAndSoftwareMember" xlink:label="loc_lpsn_ComputerEquipmentAndSoftwareMember_90FC30A9DAB7A6357CE8985E5CA66FEB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0A9B8423BF4911D37C17985E5CA6CCFB" xlink:to="loc_lpsn_ComputerEquipmentAndSoftwareMember_90FC30A9DAB7A6357CE8985E5CA66FEB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_DC06A052FD66837A14A1985E5CA6C996" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_0A9B8423BF4911D37C17985E5CA6CCFB" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_DC06A052FD66837A14A1985E5CA6C996" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_F98FBAC5A2AF7C325C61985E5CA77E76" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_F98FBAC5A2AF7C325C61985E5CA77E76" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_DABC2C27BDA7ECDD02CB985E5CA7408E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_DABC2C27BDA7ECDD02CB985E5CA7408E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_B2298803175323B93D1D985E5CA76777" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_B2298803175323B93D1D985E5CA76777" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalizedComputerSoftwareGross" xlink:label="loc_us-gaap_CapitalizedComputerSoftwareGross_8BF644738A41C01EC878985E5CA707A4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_CapitalizedComputerSoftwareGross_8BF644738A41C01EC878985E5CA707A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_EA62DFF472865550F7BF985E5CA754C2" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_EA62DFF472865550F7BF985E5CA754C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalizedContractCostNet" xlink:label="loc_us-gaap_CapitalizedContractCostNet_EF94A3B03473705BD5B8985E5CA8F709" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_CapitalizedContractCostNet_EF94A3B03473705BD5B8985E5CA8F709" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalizedContractCostAmortizationPeriod" xlink:label="loc_us-gaap_CapitalizedContractCostAmortizationPeriod_46622DE7BA71A7731AC6985E5CA818D1" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_CapitalizedContractCostAmortizationPeriod_46622DE7BA71A7731AC6985E5CA818D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_7CE14F32BBE50170EBE5985E5CA8F101" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_7CE14F32BBE50170EBE5985E5CA8F101" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdvertisingExpense" xlink:label="loc_us-gaap_AdvertisingExpense_46C0F3DB33FCDD6882FB985E5CA89D04" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_AdvertisingExpense_46C0F3DB33FCDD6882FB985E5CA89D04" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_4B6C88910962D1D13068985E5CA8BE7A" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_4B6C88910962D1D13068985E5CA8BE7A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_FCCF810C06609B22A613985E5CA830E9" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_FCCF810C06609B22A613985E5CA830E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability_57D72FA1B10FB133E712985E5CA954C8" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_OrganizationConsolidationAndSummaryOfSignificantAccountingPoliciesLineItems_9EEE3A53585E5797BF42985E5CA7E77E" xlink:to="loc_us-gaap_OperatingLeaseLiability_57D72FA1B10FB133E712985E5CA954C8" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesReclassificationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems" xlink:label="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9BA013BAFEAA874F3E7F985E5C762E23" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable" xlink:label="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_EB1A08ADBE2FF92B22E2985E5C75D8DF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9BA013BAFEAA874F3E7F985E5C762E23" xlink:to="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_EB1A08ADBE2FF92B22E2985E5C75D8DF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RestatementAxis" xlink:label="loc_srt_RestatementAxis_C83B68EC1B0FA8946534985E5C75EC59" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfErrorCorrectionsAndPriorPeriodAdjustmentRestatementTable_EB1A08ADBE2FF92B22E2985E5C75D8DF" xlink:to="loc_srt_RestatementAxis_C83B68EC1B0FA8946534985E5C75EC59" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RestatementDomain" xlink:label="loc_srt_RestatementDomain_1B27D5D3D83F66BB9DAA985E5C7624DA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_C83B68EC1B0FA8946534985E5C75EC59" xlink:to="loc_srt_RestatementDomain_1B27D5D3D83F66BB9DAA985E5C7624DA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RestatementDomain" xlink:label="loc_srt_RestatementDomain_1B27D5D3D83F66BB9DAA985E5C7624DA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_C83B68EC1B0FA8946534985E5C75EC59" xlink:to="loc_srt_RestatementDomain_1B27D5D3D83F66BB9DAA985E5C7624DA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ScenarioPreviouslyReportedMember" xlink:label="loc_srt_ScenarioPreviouslyReportedMember_9CAE090542AFBCD075C6985E5C76CE03" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_1B27D5D3D83F66BB9DAA985E5C7624DA" xlink:to="loc_srt_ScenarioPreviouslyReportedMember_9CAE090542AFBCD075C6985E5C76CE03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RestatementAdjustmentMember" xlink:label="loc_srt_RestatementAdjustmentMember_82C9BFB0D339C1631C45985E5C769F25" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RestatementDomain_1B27D5D3D83F66BB9DAA985E5C7624DA" xlink:to="loc_srt_RestatementAdjustmentMember_82C9BFB0D339C1631C45985E5C769F25" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_49CE67805D7269243FB2985E5C76927C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9BA013BAFEAA874F3E7F985E5C762E23" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_49CE67805D7269243FB2985E5C76927C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_98F510C5156FA445855D9865DF06C7F0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9BA013BAFEAA874F3E7F985E5C762E23" xlink:to="loc_us-gaap_AssetsCurrent_98F510C5156FA445855D9865DF06C7F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CapitalizedContractCostNetNoncurrent" xlink:label="loc_us-gaap_CapitalizedContractCostNetNoncurrent_799F0614A88D4A703C4D985E5C779526" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ErrorCorrectionsAndPriorPeriodAdjustmentsRestatementLineItems_9BA013BAFEAA874F3E7F985E5C762E23" xlink:to="loc_us-gaap_CapitalizedContractCostNetNoncurrent_799F0614A88D4A703C4D985E5C779526" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesRevenueByGeographicRegionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_47AEB95877E89F68540D6DEF173746A3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_2B0BBA1C1770918E78EA6DEF1734B2AD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_47AEB95877E89F68540D6DEF173746A3" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_2B0BBA1C1770918E78EA6DEF1734B2AD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_F1B5BE8F43A1DA56B4626DEF1735A4B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_2B0BBA1C1770918E78EA6DEF1734B2AD" xlink:to="loc_srt_StatementGeographicalAxis_F1B5BE8F43A1DA56B4626DEF1735A4B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_F1B5BE8F43A1DA56B4626DEF1735A4B4" xlink:to="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_F1B5BE8F43A1DA56B4626DEF1735A4B4" xlink:to="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="loc_country_US_1B5D32C7AE58F528A5B06DEF1735627D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:to="loc_country_US_1B5D32C7AE58F528A5B06DEF1735627D" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_OtherAmericasMember" xlink:label="loc_lpsn_OtherAmericasMember_0CA75E40A8592EE6EB416DEF1736F25B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:to="loc_lpsn_OtherAmericasMember_0CA75E40A8592EE6EB416DEF1736F25B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_AmericasMember" xlink:label="loc_srt_AmericasMember_7016546C2B33973D256B6DEF1736AE5E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:to="loc_srt_AmericasMember_7016546C2B33973D256B6DEF1736AE5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EMEAMember" xlink:label="loc_us-gaap_EMEAMember_BFF25767802A606B05076DEF1736C95A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:to="loc_us-gaap_EMEAMember_BFF25767802A606B05076DEF1736C95A" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/exch/2019/exch-2019-01-31.xsd#exch_XPST" xlink:label="loc_exch_XPST_13E168BFB640E72D72AE6DEF1736D0E0" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:to="loc_exch_XPST_13E168BFB640E72D72AE6DEF1736D0E0" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_GB" xlink:label="loc_country_GB_C2932433FF24C2CE474F6DEF17369D36" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:to="loc_country_GB_C2932433FF24C2CE474F6DEF17369D36" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_NL" xlink:label="loc_country_NL_352F9B0491EDF7EE851A6DEF17361D0B" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_F1980D8F1C3A2EA1757B6DEF17351C35" xlink:to="loc_country_NL_352F9B0491EDF7EE851A6DEF17361D0B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1BF5A314350CD76097526E2EA170A4BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_47AEB95877E89F68540D6DEF173746A3" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1BF5A314350CD76097526E2EA170A4BC" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/FairValueMeasurements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/FairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_F97C8008D52E4F3A92CC663FD9F12DC8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7987212DB0022A72875A663FD9EE08C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_F97C8008D52E4F3A92CC663FD9F12DC8" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7987212DB0022A72875A663FD9EE08C3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_F899987333FD353A0015663FD9EEB5F5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7987212DB0022A72875A663FD9EE08C3" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_F899987333FD353A0015663FD9EEB5F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_2BAD9CC5813270E1FAE2663FD9EEE795_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_F899987333FD353A0015663FD9EEB5F5" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_2BAD9CC5813270E1FAE2663FD9EEE795_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_2BAD9CC5813270E1FAE2663FD9EEE795" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_F899987333FD353A0015663FD9EEB5F5" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_2BAD9CC5813270E1FAE2663FD9EEE795" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_C4F27A6725309217D503663FD9EFAC1D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_2BAD9CC5813270E1FAE2663FD9EEE795" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_C4F27A6725309217D503663FD9EFAC1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B23258EC79F800730893663FD9EF53FF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7987212DB0022A72875A663FD9EE08C3" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B23258EC79F800730893663FD9EF53FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68610087F65B0B4ECD40663FD9EF236E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B23258EC79F800730893663FD9EF53FF" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68610087F65B0B4ECD40663FD9EF236E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68610087F65B0B4ECD40663FD9EF236E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B23258EC79F800730893663FD9EF53FF" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68610087F65B0B4ECD40663FD9EF236E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_8A26CE06CB805DCC856F663FD9EF6C20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68610087F65B0B4ECD40663FD9EF236E" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_8A26CE06CB805DCC856F663FD9EF6C20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_AB5280D4F4B02DFF43FF663FD9F0C826" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68610087F65B0B4ECD40663FD9EF236E" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_AB5280D4F4B02DFF43FF663FD9F0C826" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_84A928ADF25E4FB7300E663FD9F0C4F3" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_68610087F65B0B4ECD40663FD9EF236E" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_84A928ADF25E4FB7300E663FD9F0C4F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_80F4716728F50646754C663FD9F0C9BC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7987212DB0022A72875A663FD9EE08C3" xlink:to="loc_us-gaap_FinancialInstrumentAxis_80F4716728F50646754C663FD9F0C9BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9FDECF2CDED371E8A8A4663FD9F0ECAB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_80F4716728F50646754C663FD9F0C9BC" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9FDECF2CDED371E8A8A4663FD9F0ECAB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9FDECF2CDED371E8A8A4663FD9F0ECAB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_80F4716728F50646754C663FD9F0C9BC" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9FDECF2CDED371E8A8A4663FD9F0ECAB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="loc_us-gaap_MoneyMarketFundsMember_F2EF6E3A23DF080DD098663FD9F00E6B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9FDECF2CDED371E8A8A4663FD9F0ECAB" xlink:to="loc_us-gaap_MoneyMarketFundsMember_F2EF6E3A23DF080DD098663FD9F00E6B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ContingentEarnOutMember" xlink:label="loc_lpsn_ContingentEarnOutMember_F3A1484ACEA4A3FFDC04663FD9F14E41" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_9FDECF2CDED371E8A8A4663FD9F0ECAB" xlink:to="loc_lpsn_ContingentEarnOutMember_F3A1484ACEA4A3FFDC04663FD9F14E41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_E73853F4D73EB77D9F88663FD9F1F0BF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_F97C8008D52E4F3A92CC663FD9F12DC8" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_E73853F4D73EB77D9F88663FD9F1F0BF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_8AEE91D7C9B6FBD97BDF663FD9F1F3A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_E73853F4D73EB77D9F88663FD9F1F0BF" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_8AEE91D7C9B6FBD97BDF663FD9F1F3A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_615316F260A8904DECD2663FD9F25BBD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_E73853F4D73EB77D9F88663FD9F1F0BF" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_615316F260A8904DECD2663FD9F25BBD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_24EA86CDDEBACA52D8FD663FD9F27F5F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_F97C8008D52E4F3A92CC663FD9F12DC8" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_24EA86CDDEBACA52D8FD663FD9F27F5F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_517F51D76412EAC347DF663FD9F209C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_24EA86CDDEBACA52D8FD663FD9F27F5F" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_517F51D76412EAC347DF663FD9F209C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_46693021429D3FF54A08663FD9F3A917" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_24EA86CDDEBACA52D8FD663FD9F27F5F" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_46693021429D3FF54A08663FD9F3A917" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/FairValueMeasurementsDerivativeFinancialInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_ABFC279599547FD5D05265AF1BEE1B93" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_5C9F4AF4F0EAE16E2BFC65AF1BEC8141" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_ABFC279599547FD5D05265AF1BEE1B93" xlink:to="loc_us-gaap_DerivativeTable_5C9F4AF4F0EAE16E2BFC65AF1BEC8141" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_4D741984531D7758145D65AF1BECFEE9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_5C9F4AF4F0EAE16E2BFC65AF1BEC8141" xlink:to="loc_us-gaap_HedgingDesignationAxis_4D741984531D7758145D65AF1BECFEE9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_96D426B30E31EA2E87BF65AF1BECDE14_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_4D741984531D7758145D65AF1BECFEE9" xlink:to="loc_us-gaap_HedgingDesignationDomain_96D426B30E31EA2E87BF65AF1BECDE14_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_96D426B30E31EA2E87BF65AF1BECDE14" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_4D741984531D7758145D65AF1BECFEE9" xlink:to="loc_us-gaap_HedgingDesignationDomain_96D426B30E31EA2E87BF65AF1BECDE14" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_2380FB094FA7E5CE688F65AF1BED93A1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_96D426B30E31EA2E87BF65AF1BECDE14" xlink:to="loc_us-gaap_NondesignatedMember_2380FB094FA7E5CE688F65AF1BED93A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_AAC6C344DECBCB06942165AF1BED09F5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_5C9F4AF4F0EAE16E2BFC65AF1BEC8141" xlink:to="loc_us-gaap_FinancialInstrumentAxis_AAC6C344DECBCB06942165AF1BED09F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_581516A59AC0CE29059E65AF1BED67F0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_AAC6C344DECBCB06942165AF1BED09F5" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_581516A59AC0CE29059E65AF1BED67F0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_581516A59AC0CE29059E65AF1BED67F0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_AAC6C344DECBCB06942165AF1BED09F5" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_581516A59AC0CE29059E65AF1BED67F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ForeignExchangeForwardMember" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_97B5038A675EE2A8A4C765AF1BED9C40" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_581516A59AC0CE29059E65AF1BED67F0" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_97B5038A675EE2A8A4C765AF1BED9C40" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_29EF8BEB3C6421E460FE65AF1BEDA64A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_5C9F4AF4F0EAE16E2BFC65AF1BEC8141" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_29EF8BEB3C6421E460FE65AF1BEDA64A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3F603A8F65EF3323C38965AF1BEE9346_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_29EF8BEB3C6421E460FE65AF1BEDA64A" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3F603A8F65EF3323C38965AF1BEE9346_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3F603A8F65EF3323C38965AF1BEE9346" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_29EF8BEB3C6421E460FE65AF1BEDA64A" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3F603A8F65EF3323C38965AF1BEE9346" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseMember" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpenseMember_2C0E77B6D1ABBEAA205965AF1BEE24FC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3F603A8F65EF3323C38965AF1BEE9346" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpenseMember_2C0E77B6D1ABBEAA205965AF1BEE24FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrealizedGainLossOnDerivatives" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_0ABC8F5C434EACEDC93065AF1BEE71F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_ABFC279599547FD5D05265AF1BEE1B93" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_0ABC8F5C434EACEDC93065AF1BEE71F3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/FairValueMeasurementsLevel3LiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_C8F7E3A5D9C035AF22E4663FD9E77FB2" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_841FC0D721E2EEC9597C663FD9E5B402" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_C8F7E3A5D9C035AF22E4663FD9E77FB2" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_841FC0D721E2EEC9597C663FD9E5B402" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_19D2D892E92A1A0032A3663FD9E5C437" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_841FC0D721E2EEC9597C663FD9E5B402" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_19D2D892E92A1A0032A3663FD9E5C437" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A511C06565A69114A3FF663FD9E66295_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_19D2D892E92A1A0032A3663FD9E5C437" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A511C06565A69114A3FF663FD9E66295_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A511C06565A69114A3FF663FD9E66295" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_19D2D892E92A1A0032A3663FD9E5C437" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A511C06565A69114A3FF663FD9E66295" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ContingentEarnOutMember" xlink:label="loc_lpsn_ContingentEarnOutMember_03A2D03E906C8720CAF0663FD9E60084" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_A511C06565A69114A3FF663FD9E66295" xlink:to="loc_lpsn_ContingentEarnOutMember_03A2D03E906C8720CAF0663FD9E60084" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_3DFB6B5811D6B6F40C3F663FD9E62BE2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_841FC0D721E2EEC9597C663FD9E5B402" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_3DFB6B5811D6B6F40C3F663FD9E62BE2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_DC54E6479D4B7857CCB1663FD9E63F97_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3DFB6B5811D6B6F40C3F663FD9E62BE2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_DC54E6479D4B7857CCB1663FD9E63F97_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_DC54E6479D4B7857CCB1663FD9E63F97" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_3DFB6B5811D6B6F40C3F663FD9E62BE2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_DC54E6479D4B7857CCB1663FD9E63F97" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConversableIncMember" xlink:label="loc_lpsn_ConversableIncMember_9E590C3289CCCE7347C6663FD9E70A57" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_DC54E6479D4B7857CCB1663FD9E63F97" xlink:to="loc_lpsn_ConversableIncMember_9E590C3289CCCE7347C6663FD9E70A57" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AdvantageTecIncMember" xlink:label="loc_lpsn_AdvantageTecIncMember_3FE22505190D89EF57BA663FD9E7EA40" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_DC54E6479D4B7857CCB1663FD9E63F97" xlink:to="loc_lpsn_AdvantageTecIncMember_3FE22505190D89EF57BA663FD9E7EA40" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_EB84E3B4515C905E7B4D663FD9E799D2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_C8F7E3A5D9C035AF22E4663FD9E77FB2" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_EB84E3B4515C905E7B4D663FD9E799D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_DDF702CF2E8E90B6C66D663FD9E796F7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_EB84E3B4515C905E7B4D663FD9E799D2" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_DDF702CF2E8E90B6C66D663FD9E796F7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases_9000CF2CBCE3A10C8F6C663FD9E89524" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_EB84E3B4515C905E7B4D663FD9E799D2" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases_9000CF2CBCE3A10C8F6C663FD9E89524" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments" xlink:label="loc_lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments_6FA366DCCEC4C480F244663FD9E8390D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_EB84E3B4515C905E7B4D663FD9E799D2" xlink:to="loc_lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments_6FA366DCCEC4C480F244663FD9E8390D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_EC2E02BA2F5A8A8C8D4E663FD9E8E177" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward_EB84E3B4515C905E7B4D663FD9E799D2" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements_EC2E02BA2F5A8A8C8D4E663FD9E8E177" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_68F79CBBE98EE474CC94663FD9FA794A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8E5C37EFECB19CA47320663FD9F82758" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_68F79CBBE98EE474CC94663FD9FA794A" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8E5C37EFECB19CA47320663FD9F82758" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4C4C14684A660AADC41D66AE10AC1F7B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8E5C37EFECB19CA47320663FD9F82758" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4C4C14684A660AADC41D66AE10AC1F7B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_98D2511C2FA7CEAE2B6066AE10D30237_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4C4C14684A660AADC41D66AE10AC1F7B" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_98D2511C2FA7CEAE2B6066AE10D30237_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_98D2511C2FA7CEAE2B6066AE10D30237" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4C4C14684A660AADC41D66AE10AC1F7B" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_98D2511C2FA7CEAE2B6066AE10D30237" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_7627A9D701C89AA4740B66AE3CD762B8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_98D2511C2FA7CEAE2B6066AE10D30237" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_7627A9D701C89AA4740B66AE3CD762B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3FFCDB2675A25C6A6353669932B64515" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8E5C37EFECB19CA47320663FD9F82758" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3FFCDB2675A25C6A6353669932B64515" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_9B47AA51460391DF96B3669932BD7ECF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3FFCDB2675A25C6A6353669932B64515" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_9B47AA51460391DF96B3669932BD7ECF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_9B47AA51460391DF96B3669932BD7ECF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3FFCDB2675A25C6A6353669932B64515" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_9B47AA51460391DF96B3669932BD7ECF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_8C8D7A66CE33715A9A10669932F5A1D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_9B47AA51460391DF96B3669932BD7ECF" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_8C8D7A66CE33715A9A10669932F5A1D0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_33A0A3F656F22AADB243663FD9F8A5F1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8E5C37EFECB19CA47320663FD9F82758" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_33A0A3F656F22AADB243663FD9F8A5F1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_6AE626B5CC65B15BA342663FD9F8B6D6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_33A0A3F656F22AADB243663FD9F8A5F1" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_6AE626B5CC65B15BA342663FD9F8B6D6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_6AE626B5CC65B15BA342663FD9F8B6D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_33A0A3F656F22AADB243663FD9F8A5F1" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_6AE626B5CC65B15BA342663FD9F8B6D6" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ContingentEarnOutMember" xlink:label="loc_lpsn_ContingentEarnOutMember_BD157E4CBB1F19163FBC663FD9F8B9FC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_6AE626B5CC65B15BA342663FD9F8B6D6" xlink:to="loc_lpsn_ContingentEarnOutMember_BD157E4CBB1F19163FBC663FD9F8B9FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_49D2F1239FB54EC3F13A663FD9F99A9A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8E5C37EFECB19CA47320663FD9F82758" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_49D2F1239FB54EC3F13A663FD9F99A9A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_A0016AD67892F86766F6663FD9F9A0A5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_49D2F1239FB54EC3F13A663FD9F99A9A" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_A0016AD67892F86766F6663FD9F9A0A5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_A0016AD67892F86766F6663FD9F9A0A5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_49D2F1239FB54EC3F13A663FD9F99A9A" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_A0016AD67892F86766F6663FD9F9A0A5" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConversableIncAndAdvntageTecIncMember" xlink:label="loc_lpsn_ConversableIncAndAdvntageTecIncMember_750F36EDF8BD0F12EF81663FD9F9D865" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_A0016AD67892F86766F6663FD9F9A0A5" xlink:to="loc_lpsn_ConversableIncAndAdvntageTecIncMember_750F36EDF8BD0F12EF81663FD9F9D865" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConversableIncMember" xlink:label="loc_lpsn_ConversableIncMember_DB0CD905F4FC599ACACB663FD9FAE6EC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_A0016AD67892F86766F6663FD9F9A0A5" xlink:to="loc_lpsn_ConversableIncMember_DB0CD905F4FC599ACACB663FD9FAE6EC" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AdvantageTecIncMember" xlink:label="loc_lpsn_AdvantageTecIncMember_BECD62CFD374B93AD9FE663FD9FA8D0A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_A0016AD67892F86766F6663FD9F9A0A5" xlink:to="loc_lpsn_AdvantageTecIncMember_BECD62CFD374B93AD9FE663FD9FA8D0A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_2A00B752386085A885DF669932D3F0C7" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_8E5C37EFECB19CA47320663FD9F82758" xlink:to="loc_us-gaap_FinancialInstrumentAxis_2A00B752386085A885DF669932D3F0C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4FEE12D766569D727D21669932D9D41C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_2A00B752386085A885DF669932D3F0C7" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4FEE12D766569D727D21669932D9D41C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4FEE12D766569D727D21669932D9D41C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_2A00B752386085A885DF669932D3F0C7" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4FEE12D766569D727D21669932D9D41C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeniorDebtObligationsMember" xlink:label="loc_us-gaap_SeniorDebtObligationsMember_F34D779330DBCE2E686A66993302CF45" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_4FEE12D766569D727D21669932D9D41C" xlink:to="loc_us-gaap_SeniorDebtObligationsMember_F34D779330DBCE2E686A66993302CF45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConvertibleDebtFairValueDisclosures" xlink:label="loc_us-gaap_ConvertibleDebtFairValueDisclosures_39C11ABB2CAD495A193A66993278B404" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_68F79CBBE98EE474CC94663FD9FA794A" xlink:to="loc_us-gaap_ConvertibleDebtFairValueDisclosures_39C11ABB2CAD495A193A66993278B404" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_AC3E79E3907580E6310C663FD9FA05EF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_68F79CBBE98EE474CC94663FD9FA794A" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_AC3E79E3907580E6310C663FD9FA05EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_17DEF6E67A635EEF54946699328D88D7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_68F79CBBE98EE474CC94663FD9FA794A" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPeriodIncreaseDecrease_17DEF6E67A635EEF54946699328D88D7" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments" xlink:label="loc_lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments_7977F9AD66332759622B663FD9FA4517" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_68F79CBBE98EE474CC94663FD9FA794A" xlink:to="loc_lpsn_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisLiabilityFairValueAdjustments_7977F9AD66332759622B663FD9FA4517" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities" xlink:label="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_AFFFBABA79095BCF25C366A8AF36ACA8" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_68F79CBBE98EE474CC94663FD9FA794A" xlink:to="loc_us-gaap_PaymentForContingentConsiderationLiabilityFinancingActivities_AFFFBABA79095BCF25C366A8AF36ACA8" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_PaymentForContingentConsiderationValueEquitySharesIssued" xlink:label="loc_lpsn_PaymentForContingentConsiderationValueEquitySharesIssued_5871180A9ED86528185966ACB3A3ADF3" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_68F79CBBE98EE474CC94663FD9FA794A" xlink:to="loc_lpsn_PaymentForContingentConsiderationValueEquitySharesIssued_5871180A9ED86528185966ACB3A3ADF3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/GoodwillAndIntangibleAssets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsChangesInCarryingAmountOfGoodwillDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_E38BFE14FC269527602F663FDA4EFEED" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_2C0C7B55E3418688A891663FDA4D69D3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_E38BFE14FC269527602F663FDA4EFEED" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_2C0C7B55E3418688A891663FDA4D69D3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_BDE5D202A298FB8D6349663FDA4D03C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_2C0C7B55E3418688A891663FDA4D69D3" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_BDE5D202A298FB8D6349663FDA4D03C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_5128793DA70C488CA574663FDA4DA44B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_BDE5D202A298FB8D6349663FDA4D03C3" xlink:to="loc_us-gaap_SegmentDomain_5128793DA70C488CA574663FDA4DA44B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_5128793DA70C488CA574663FDA4DA44B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_BDE5D202A298FB8D6349663FDA4D03C3" xlink:to="loc_us-gaap_SegmentDomain_5128793DA70C488CA574663FDA4DA44B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_BusinessMember" xlink:label="loc_lpsn_BusinessMember_130AB1C6CF23CE7125E9663FDA4D43F2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5128793DA70C488CA574663FDA4DA44B" xlink:to="loc_lpsn_BusinessMember_130AB1C6CF23CE7125E9663FDA4D43F2" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConsumerMember" xlink:label="loc_lpsn_ConsumerMember_0D0A8C5D8180EAEEE68C663FDA4E146A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5128793DA70C488CA574663FDA4DA44B" xlink:to="loc_lpsn_ConsumerMember_0D0A8C5D8180EAEEE68C663FDA4E146A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillRollForward" xlink:label="loc_us-gaap_GoodwillRollForward_C9A1465AB05D777529AD663FDA4EC5A1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_E38BFE14FC269527602F663FDA4EFEED" xlink:to="loc_us-gaap_GoodwillRollForward_C9A1465AB05D777529AD663FDA4EC5A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_B928A7D5D998EDEE1D51663FDA4ED19F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_C9A1465AB05D777529AD663FDA4EC5A1" xlink:to="loc_us-gaap_Goodwill_B928A7D5D998EDEE1D51663FDA4ED19F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillAcquiredDuringPeriod" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_61F29C2B6AEEE9D02955665C65D0AE21" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_C9A1465AB05D777529AD663FDA4EC5A1" xlink:to="loc_us-gaap_GoodwillAcquiredDuringPeriod_61F29C2B6AEEE9D02955665C65D0AE21" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_BEEF7CD07BCDCE172106663FDA4F7415" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_C9A1465AB05D777529AD663FDA4EC5A1" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_BEEF7CD07BCDCE172106663FDA4F7415" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_BF28272D7D644248B22D663FDA4F4C2B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_E38BFE14FC269527602F663FDA4EFEED" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_BF28272D7D644248B22D663FDA4F4C2B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_55B005CF6749610C59F3663FDA4F5BE7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_E38BFE14FC269527602F663FDA4EFEED" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_55B005CF6749610C59F3663FDA4F5BE7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsSummaryOfAmortizationExpenseDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_BB90A5B3D543B04E5EAB663FDA483293" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_838D42914AF572ECC41D663FDA4601DD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_BB90A5B3D543B04E5EAB663FDA483293" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_838D42914AF572ECC41D663FDA4601DD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A9A5E8C88AA94E665A14663FDA46FD43" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_838D42914AF572ECC41D663FDA4601DD" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A9A5E8C88AA94E665A14663FDA46FD43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8DDB44D440C081C1A731663FDA4637BA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A9A5E8C88AA94E665A14663FDA46FD43" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8DDB44D440C081C1A731663FDA4637BA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8DDB44D440C081C1A731663FDA4637BA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_A9A5E8C88AA94E665A14663FDA46FD43" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8DDB44D440C081C1A731663FDA4637BA" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TechnologyMember" xlink:label="loc_lpsn_TechnologyMember_C80AEEA3BB3C2480F56B663FDA475C79" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8DDB44D440C081C1A731663FDA4637BA" xlink:to="loc_lpsn_TechnologyMember_C80AEEA3BB3C2480F56B663FDA475C79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CustomerContractsMember" xlink:label="loc_us-gaap_CustomerContractsMember_F754F7247170D4C1EE3E663FDA47DEF3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8DDB44D440C081C1A731663FDA4637BA" xlink:to="loc_us-gaap_CustomerContractsMember_F754F7247170D4C1EE3E663FDA47DEF3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaap_PatentsMember_14A5DADFE9B0D44AFC6F663FDA47B2C1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8DDB44D440C081C1A731663FDA4637BA" xlink:to="loc_us-gaap_PatentsMember_14A5DADFE9B0D44AFC6F663FDA47B2C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherIntangibleAssetsMember" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_DCA283ECF8044A476355663FDA48F228" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_8DDB44D440C081C1A731663FDA4637BA" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_DCA283ECF8044A476355663FDA48F228" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_C6249CEB935999190D6B663FDA486B3F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_BB90A5B3D543B04E5EAB663FDA483293" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_C6249CEB935999190D6B663FDA486B3F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_EA34A33D6BA85FFDA845663FDA489985" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_BB90A5B3D543B04E5EAB663FDA483293" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_EA34A33D6BA85FFDA845663FDA489985" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_44982C4C28F571CC27FA663FDA483053" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_BB90A5B3D543B04E5EAB663FDA483293" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_44982C4C28F571CC27FA663FDA483053" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_107CB3174E96573034B7663FDA48BB71" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_BB90A5B3D543B04E5EAB663FDA483293" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_107CB3174E96573034B7663FDA48BB71" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/IncomeTaxesDomesticAndForeignComponentsOfIncomeBeforeProvisionForIncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxContingencyLineItems" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_70758CAEB4706F13C91BFBADD3AD0044" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxContingencyTable" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_0AAE3741C688E007FD52FBADD3AD32AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_70758CAEB4706F13C91BFBADD3AD0044" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_0AAE3741C688E007FD52FBADD3AD32AB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_85971F8A2B980B6AFAE1FBADD3AD19D3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_0AAE3741C688E007FD52FBADD3AD32AB" xlink:to="loc_srt_StatementGeographicalAxis_85971F8A2B980B6AFAE1FBADD3AD19D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_85971F8A2B980B6AFAE1FBADD3AD19D3" xlink:to="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_85971F8A2B980B6AFAE1FBADD3AD19D3" xlink:to="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_IL" xlink:label="loc_country_IL_D48FCCF1CCB233564FEFFBADD3AD27EF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9" xlink:to="loc_country_IL_D48FCCF1CCB233564FEFFBADD3AD27EF" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_GB" xlink:label="loc_country_GB_A47C64C0D90B1BCE04B2FBADD3ADF7AF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9" xlink:to="loc_country_GB_A47C64C0D90B1BCE04B2FBADD3ADF7AF" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_NL" xlink:label="loc_country_NL_3349FB2EF9D20AEC58C2FBADD3AD8FE9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9" xlink:to="loc_country_NL_3349FB2EF9D20AEC58C2FBADD3AD8FE9" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_AU" xlink:label="loc_country_AU_84E3CC27E5163FAC432BFBADD3AD3E85" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9" xlink:to="loc_country_AU_84E3CC27E5163FAC432BFBADD3AD3E85" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_DE" xlink:label="loc_country_DE_8A774977D17AD94D6663FBADD3AD6F97" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9" xlink:to="loc_country_DE_8A774977D17AD94D6663FBADD3AD6F97" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_JP" xlink:label="loc_country_JP_102E8341E5E74822F45FFBADD3ADBBEE" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0D86C4311978CFA37546FBADD3AD7FC9" xlink:to="loc_country_JP_102E8341E5E74822F45FFBADD3ADBBEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_C6069EE39F36F036DA9EFBADD3ADCBD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_70758CAEB4706F13C91BFBADD3AD0044" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic_C6069EE39F36F036DA9EFBADD3ADCBD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_B7AA46383CB96A3EE3DEFBADD3AD24FD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_70758CAEB4706F13C91BFBADD3AD0044" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign_B7AA46383CB96A3EE3DEFBADD3AD24FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_7E076496923AD07E7CD6FBADD3ADFE7C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_70758CAEB4706F13C91BFBADD3AD0044" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_7E076496923AD07E7CD6FBADD3ADFE7C" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_5ECA77BD600DE54C4B8D6DEF1622D063" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_5ECA77BD600DE54C4B8D6DEF1622D063" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_E9E3C27C462D0B59500F6DEF16224E06" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_5ECA77BD600DE54C4B8D6DEF1622D063" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_E9E3C27C462D0B59500F6DEF16224E06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_778ECEED8826F6813DC26DEF1622C5AD_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_E9E3C27C462D0B59500F6DEF16224E06" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_778ECEED8826F6813DC26DEF1622C5AD_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_778ECEED8826F6813DC26DEF1622C5AD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_E9E3C27C462D0B59500F6DEF16224E06" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_778ECEED8826F6813DC26DEF1622C5AD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DomesticCountryMember" xlink:label="loc_us-gaap_DomesticCountryMember_B078C71CF5828F8B4F146DEF1623048F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_778ECEED8826F6813DC26DEF1622C5AD" xlink:to="loc_us-gaap_DomesticCountryMember_B078C71CF5828F8B4F146DEF1623048F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ForeignCountryMember" xlink:label="loc_us-gaap_ForeignCountryMember_EE1A3B272680E1CBEA176DEF16230D57" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_778ECEED8826F6813DC26DEF1622C5AD" xlink:to="loc_us-gaap_ForeignCountryMember_EE1A3B272680E1CBEA176DEF16230D57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityNameAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameAxis_482FF81F6D6B009EDA986DEF1623DB07" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_5ECA77BD600DE54C4B8D6DEF1622D063" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameAxis_482FF81F6D6B009EDA986DEF1623DB07" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityNameDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_C43C6539B8E38D78B20A6DEF16232EE6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_482FF81F6D6B009EDA986DEF1623DB07" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_C43C6539B8E38D78B20A6DEF16232EE6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxAuthorityNameDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_C43C6539B8E38D78B20A6DEF16232EE6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_482FF81F6D6B009EDA986DEF1623DB07" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_C43C6539B8E38D78B20A6DEF16232EE6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AustralianTaxationOfficeMember" xlink:label="loc_us-gaap_AustralianTaxationOfficeMember_E00D229D5BCD47DDC0E86DEF16244D83" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_C43C6539B8E38D78B20A6DEF16232EE6" xlink:to="loc_us-gaap_AustralianTaxationOfficeMember_E00D229D5BCD47DDC0E86DEF16244D83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_62D24C8743C6D0D335086DEF1624CE6C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_5ECA77BD600DE54C4B8D6DEF1622D063" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_62D24C8743C6D0D335086DEF1624CE6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0FA682DF3D91D00327F66DEF1624EF98_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_62D24C8743C6D0D335086DEF1624CE6C" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0FA682DF3D91D00327F66DEF1624EF98_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0FA682DF3D91D00327F66DEF1624EF98" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_62D24C8743C6D0D335086DEF1624CE6C" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0FA682DF3D91D00327F66DEF1624EF98" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ProficientMember" xlink:label="loc_lpsn_ProficientMember_BF06FA7D953A4D21E38D6DEF16241346" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_0FA682DF3D91D00327F66DEF1624EF98" xlink:to="loc_lpsn_ProficientMember_BF06FA7D953A4D21E38D6DEF16241346" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_NetOperatingLossExpirationPeriodsAxis" xlink:label="loc_lpsn_NetOperatingLossExpirationPeriodsAxis_399E0F400AF8D58FD63D6DEF1625588B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_5ECA77BD600DE54C4B8D6DEF1622D063" xlink:to="loc_lpsn_NetOperatingLossExpirationPeriodsAxis_399E0F400AF8D58FD63D6DEF1625588B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_NetOperatingLossExpirationPeriodsDomain" xlink:label="loc_lpsn_NetOperatingLossExpirationPeriodsDomain_0100F1340F5ADF93E2F66DEF16259457_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_lpsn_NetOperatingLossExpirationPeriodsAxis_399E0F400AF8D58FD63D6DEF1625588B" xlink:to="loc_lpsn_NetOperatingLossExpirationPeriodsDomain_0100F1340F5ADF93E2F66DEF16259457_default" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_NetOperatingLossExpirationPeriodsDomain" xlink:label="loc_lpsn_NetOperatingLossExpirationPeriodsDomain_0100F1340F5ADF93E2F66DEF16259457" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_lpsn_NetOperatingLossExpirationPeriodsAxis_399E0F400AF8D58FD63D6DEF1625588B" xlink:to="loc_lpsn_NetOperatingLossExpirationPeriodsDomain_0100F1340F5ADF93E2F66DEF16259457" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_NOLExpirationPeriodTrancheOneMember" xlink:label="loc_lpsn_NOLExpirationPeriodTrancheOneMember_8B6DCCBDEF7EA63CC0216DEF16254135" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_NetOperatingLossExpirationPeriodsDomain_0100F1340F5ADF93E2F66DEF16259457" xlink:to="loc_lpsn_NOLExpirationPeriodTrancheOneMember_8B6DCCBDEF7EA63CC0216DEF16254135" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_NOLExpirationPeriodTrancheTwoMember" xlink:label="loc_lpsn_NOLExpirationPeriodTrancheTwoMember_5C924F95B15A7411D9A66DEF16253E96" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_NetOperatingLossExpirationPeriodsDomain_0100F1340F5ADF93E2F66DEF16259457" xlink:to="loc_lpsn_NOLExpirationPeriodTrancheTwoMember_5C924F95B15A7411D9A66DEF16253E96" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ValuationAllowancesAndReservesPeriodIncreaseDecrease" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesPeriodIncreaseDecrease_B02F06AF354C2AE1A9F86DEF1626B3E4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesPeriodIncreaseDecrease_B02F06AF354C2AE1A9F86DEF1626B3E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLossCarryforwards" xlink:label="loc_us-gaap_OperatingLossCarryforwards_E20D2934D545EC72BB916DEF16260B6F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_OperatingLossCarryforwards_E20D2934D545EC72BB916DEF16260B6F" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_OperatingLossCarryforwardsGeneratedInTaxableYearsEndingOnOrBeforeDecember312017" xlink:label="loc_lpsn_OperatingLossCarryforwardsGeneratedInTaxableYearsEndingOnOrBeforeDecember312017_742A8E420EB836C9D2FB6DEF162610E9" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_lpsn_OperatingLossCarryforwardsGeneratedInTaxableYearsEndingOnOrBeforeDecember312017_742A8E420EB836C9D2FB6DEF162610E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_B61D92C624A83B93F82D6DEF16269904" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsNotSubjectToExpiration_B61D92C624A83B93F82D6DEF16269904" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_D0888F5582D1CE2450D46DEF1627E587" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration_D0888F5582D1CE2450D46DEF1627E587" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefits" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_850BBFD7B660B5DBBAFD6DEF1627156A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_850BBFD7B660B5DBBAFD6DEF1627156A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_F8B41268B38EEFF3712A6E8E70129A33" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_F8B41268B38EEFF3712A6E8E70129A33" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_OperatingLossCarryforwardsCarryforwardPeriod" xlink:label="loc_lpsn_OperatingLossCarryforwardsCarryforwardPeriod_1C8C8DAB371C163DF7086DEF16271CDF" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_lpsn_OperatingLossCarryforwardsCarryforwardPeriod_1C8C8DAB371C163DF7086DEF16271CDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit_BC8227C99C82FB4DE1B56DEF162779B8" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit_BC8227C99C82FB4DE1B56DEF162779B8" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TaxCutsandJobsActof2017IncompleteAccountingChangeinTaxRateOnValuationAllowanceProvisionalIncomeTaxExpenseBenefit" xlink:label="loc_lpsn_TaxCutsandJobsActof2017IncompleteAccountingChangeinTaxRateOnValuationAllowanceProvisionalIncomeTaxExpenseBenefit_80FFA6679A21417153BE6DEF162899BC" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_lpsn_TaxCutsandJobsActof2017IncompleteAccountingChangeinTaxRateOnValuationAllowanceProvisionalIncomeTaxExpenseBenefit_80FFA6679A21417153BE6DEF162899BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateDeferredTaxLiabilityProvisionalIncomeTaxBenefit" xlink:label="loc_us-gaap_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateDeferredTaxLiabilityProvisionalIncomeTaxBenefit_870D61A6BDB21129CD836DEF162851AD" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateDeferredTaxLiabilityProvisionalIncomeTaxBenefit_870D61A6BDB21129CD836DEF162851AD" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_DeferredTaxLiabilitiesIndefiniteLivedPercentUtilized" xlink:label="loc_lpsn_DeferredTaxLiabilitiesIndefiniteLivedPercentUtilized_66DA8F5CFE534ABDB54A6DEF1628351B" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_lpsn_DeferredTaxLiabilitiesIndefiniteLivedPercentUtilized_66DA8F5CFE534ABDB54A6DEF1628351B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_777D30304DD5DD09A6F56DEF1628A531" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_3CAC2A9E73BFD2E99A596DEF16269C26" xlink:to="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_777D30304DD5DD09A6F56DEF1628A531" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/IncomeTaxesScheduleOfFederalDeferredTaxAssetsAndDeferredTaxLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/IncomeTaxesScheduleOfProvisionForIncomeTaxesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/IncomeTaxesScheduleOfReconciliationsOfFederalStatutoryTaxRateToEffectiveIncomeTaxRateDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/IncomeTaxesScheduleOfUnrecognizedTaxBenefitsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/IncomeTaxesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/LegalMatters" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/NetLossPerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/NetLossPerShareDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/NetLossPerShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/PropertyAndEquipment" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/PropertyAndEquipmentBalancesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_2B4D0ABDD9EE84BBB22765AF1CADAF4D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_D3D4CB56AF8DA5ACD1CB65AF1CAC408C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_2B4D0ABDD9EE84BBB22765AF1CADAF4D" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_D3D4CB56AF8DA5ACD1CB65AF1CAC408C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_DDFEED53A05514C2C5CA65AF1CACB4FF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_D3D4CB56AF8DA5ACD1CB65AF1CAC408C" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_DDFEED53A05514C2C5CA65AF1CACB4FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5BB0D7AEA462D1FC8B1A65AF1CAD671D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_DDFEED53A05514C2C5CA65AF1CACB4FF" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5BB0D7AEA462D1FC8B1A65AF1CAD671D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5BB0D7AEA462D1FC8B1A65AF1CAD671D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_DDFEED53A05514C2C5CA65AF1CACB4FF" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5BB0D7AEA462D1FC8B1A65AF1CAD671D" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ComputerEquipmentAndSoftwareMember" xlink:label="loc_lpsn_ComputerEquipmentAndSoftwareMember_C30F4AB3F95AC9C4F76B65AF1CAD680E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5BB0D7AEA462D1FC8B1A65AF1CAD671D" xlink:to="loc_lpsn_ComputerEquipmentAndSoftwareMember_C30F4AB3F95AC9C4F76B65AF1CAD680E" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_FurnitureEquipmentAndBuildingImprovementsMember" xlink:label="loc_lpsn_FurnitureEquipmentAndBuildingImprovementsMember_87F28819E8D8E5F1B5B365AF1CAD2A1F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5BB0D7AEA462D1FC8B1A65AF1CAD671D" xlink:to="loc_lpsn_FurnitureEquipmentAndBuildingImprovementsMember_87F28819E8D8E5F1B5B365AF1CAD2A1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SoftwareDevelopmentMember" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_2AB4A3D70AFDA6C9114F65AF1CADF20D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_5BB0D7AEA462D1FC8B1A65AF1CAD671D" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_2AB4A3D70AFDA6C9114F65AF1CADF20D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNetByTypeAbstract" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetByTypeAbstract_50B7435B7C1CB462073965AF1CAE20EF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_2B4D0ABDD9EE84BBB22765AF1CADAF4D" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetByTypeAbstract_50B7435B7C1CB462073965AF1CAE20EF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_A09A6B8A7284FCC5132D65AF1CAE8720" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetByTypeAbstract_50B7435B7C1CB462073965AF1CAE20EF" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_A09A6B8A7284FCC5132D65AF1CAE8720" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_913D55B3F7C120DB236465AF1CAFEE0B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetByTypeAbstract_50B7435B7C1CB462073965AF1CAE20EF" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_913D55B3F7C120DB236465AF1CAFEE0B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_E740970C71A5405425AC65AF1CAFC637" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetByTypeAbstract_50B7435B7C1CB462073965AF1CAE20EF" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_E740970C71A5405425AC65AF1CAFC637" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/PropertyAndEquipmentNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/PropertyAndEquipmentTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringCosts" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringCostsComponentsOfRestructuringChargesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringCostsExpensesRelatedToRestructuringChargesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_D2836B3D1BFBED87314A663FD90E8B38" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_2364A1A6DB79C06F01E0663FD90CDEFA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_D2836B3D1BFBED87314A663FD90E8B38" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_2364A1A6DB79C06F01E0663FD90CDEFA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_24B162E26ADBCEBA641C663FD90D78E7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_2364A1A6DB79C06F01E0663FD90CDEFA" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_24B162E26ADBCEBA641C663FD90D78E7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_15F19D8CB4840FF7CD66663FD90D9286_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_24B162E26ADBCEBA641C663FD90D78E7" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_15F19D8CB4840FF7CD66663FD90D9286_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_15F19D8CB4840FF7CD66663FD90D9286" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_24B162E26ADBCEBA641C663FD90D78E7" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_15F19D8CB4840FF7CD66663FD90D9286" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_574C8F503ED296607A04663FD90EA415" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_15F19D8CB4840FF7CD66663FD90D9286" xlink:to="loc_us-gaap_EmployeeSeveranceMember_574C8F503ED296607A04663FD90EA415" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_WindDownCostsMember" xlink:label="loc_lpsn_WindDownCostsMember_8D4FBBC64AF9903BDF32663FD90EA251" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_15F19D8CB4840FF7CD66663FD90D9286" xlink:to="loc_lpsn_WindDownCostsMember_8D4FBBC64AF9903BDF32663FD90EA251" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_E238CF81031B1936A093663FD90E17FD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_D2836B3D1BFBED87314A663FD90E8B38" xlink:to="loc_us-gaap_RestructuringCharges_E238CF81031B1936A093663FD90E17FD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringCostsNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringCostsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/SegmentInformation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/SegmentInformationLongLivedAssetsByGeographicRegionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_5D35F30304240E595F03FBADD2E2022C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_B6873C42946B294CEB96FBADD2E23F3C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_5D35F30304240E595F03FBADD2E2022C" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_B6873C42946B294CEB96FBADD2E23F3C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_0240C9F19C77D10EB43EFBADD2E2EA6E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_B6873C42946B294CEB96FBADD2E23F3C" xlink:to="loc_srt_StatementGeographicalAxis_0240C9F19C77D10EB43EFBADD2E2EA6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_0240C9F19C77D10EB43EFBADD2E2EA6E" xlink:to="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_0240C9F19C77D10EB43EFBADD2E2EA6E" xlink:to="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="loc_country_US_D0B9245D35AB5EB8EF68FBADD2E2E107" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF" xlink:to="loc_country_US_D0B9245D35AB5EB8EF68FBADD2E2E107" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_IL" xlink:label="loc_country_IL_BF02A54B66F215098E64FBADD2E28183" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF" xlink:to="loc_country_IL_BF02A54B66F215098E64FBADD2E28183" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_AU" xlink:label="loc_country_AU_9412FF1FEDC2ABD57861FBADD2E22228" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF" xlink:to="loc_country_AU_9412FF1FEDC2ABD57861FBADD2E22228" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_NL" xlink:label="loc_country_NL_3718D1AB3CBA5E2B3705FBADD2E2935F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF" xlink:to="loc_country_NL_3718D1AB3CBA5E2B3705FBADD2E2935F" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_UnitedKingdomGermanyJapanFranceItalyMember" xlink:label="loc_lpsn_UnitedKingdomGermanyJapanFranceItalyMember_58EE6502C1A5D4BE2463FBADD2E21EB6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_CC5D24F05E7B8462FF7FFBADD2E270DF" xlink:to="loc_lpsn_UnitedKingdomGermanyJapanFranceItalyMember_58EE6502C1A5D4BE2463FBADD2E21EB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsNoncurrent" xlink:label="loc_us-gaap_AssetsNoncurrent_33E3A708DFF948A4EDA6FBADD2E24785" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_5D35F30304240E595F03FBADD2E2022C" xlink:to="loc_us-gaap_AssetsNoncurrent_33E3A708DFF948A4EDA6FBADD2E24785" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/SegmentInformationNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/SegmentInformationSummaryOfFinancialInformationBySegmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_4768BB4016DC4CE34BAD6DEF171621FD" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ED5E78B091C4BF3E99B16DEF1713C647" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4768BB4016DC4CE34BAD6DEF171621FD" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ED5E78B091C4BF3E99B16DEF1713C647" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_2ECB385CEE63C7BB42246DEF17137E70" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ED5E78B091C4BF3E99B16DEF1713C647" xlink:to="loc_srt_ProductOrServiceAxis_2ECB385CEE63C7BB42246DEF17137E70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_50DF6D09C05E2133EC256DEF1714F522_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_2ECB385CEE63C7BB42246DEF17137E70" xlink:to="loc_srt_ProductsAndServicesDomain_50DF6D09C05E2133EC256DEF1714F522_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_50DF6D09C05E2133EC256DEF1714F522" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_2ECB385CEE63C7BB42246DEF17137E70" xlink:to="loc_srt_ProductsAndServicesDomain_50DF6D09C05E2133EC256DEF1714F522" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_HostedServicesBusinessMember" xlink:label="loc_lpsn_HostedServicesBusinessMember_63F4AECDA05E3C416DD66DEF1714436B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_50DF6D09C05E2133EC256DEF1714F522" xlink:to="loc_lpsn_HostedServicesBusinessMember_63F4AECDA05E3C416DD66DEF1714436B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_HostedServicesConsumerMember" xlink:label="loc_lpsn_HostedServicesConsumerMember_4E49A502D146750533386DEF17142951" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_50DF6D09C05E2133EC256DEF1714F522" xlink:to="loc_lpsn_HostedServicesConsumerMember_4E49A502D146750533386DEF17142951" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ProfessionalServicesMember" xlink:label="loc_lpsn_ProfessionalServicesMember_C7ECD134C008FA04CBD86DEF1714FB46" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_50DF6D09C05E2133EC256DEF1714F522" xlink:to="loc_lpsn_ProfessionalServicesMember_C7ECD134C008FA04CBD86DEF1714FB46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_572F6C3698172F5104C86DEF1714A5B5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ED5E78B091C4BF3E99B16DEF1713C647" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_572F6C3698172F5104C86DEF1714A5B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_5041019B4CE1DE46DE1E6DEF17152299_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_572F6C3698172F5104C86DEF1714A5B5" xlink:to="loc_us-gaap_SegmentDomain_5041019B4CE1DE46DE1E6DEF17152299_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_5041019B4CE1DE46DE1E6DEF17152299" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_572F6C3698172F5104C86DEF1714A5B5" xlink:to="loc_us-gaap_SegmentDomain_5041019B4CE1DE46DE1E6DEF17152299" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConsumerBusinessMember" xlink:label="loc_lpsn_ConsumerBusinessMember_566F8DD6DBE006E024E16DEF17157A59" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5041019B4CE1DE46DE1E6DEF17152299" xlink:to="loc_lpsn_ConsumerBusinessMember_566F8DD6DBE006E024E16DEF17157A59" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ConsumerMember" xlink:label="loc_lpsn_ConsumerMember_7CEE6AE73E47A6A7F8836DEF1715053B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5041019B4CE1DE46DE1E6DEF17152299" xlink:to="loc_lpsn_ConsumerMember_7CEE6AE73E47A6A7F8836DEF1715053B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_125BC19E1E4160DC3A1E6DEF1715FE61" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_ED5E78B091C4BF3E99B16DEF1713C647" xlink:to="loc_srt_ConsolidationItemsAxis_125BC19E1E4160DC3A1E6DEF1715FE61" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_9D583578547A1A565C476DEF1716A97B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_125BC19E1E4160DC3A1E6DEF1715FE61" xlink:to="loc_srt_ConsolidationItemsDomain_9D583578547A1A565C476DEF1716A97B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_9D583578547A1A565C476DEF1716A97B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_125BC19E1E4160DC3A1E6DEF1715FE61" xlink:to="loc_srt_ConsolidationItemsDomain_9D583578547A1A565C476DEF1716A97B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_FB93317F908DA1FB5D8C6DEF1716BB1F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_9D583578547A1A565C476DEF1716A97B" xlink:to="loc_us-gaap_OperatingSegmentsMember_FB93317F908DA1FB5D8C6DEF1716BB1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_051262BC937A6E6371216DEF1716B75F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_9D583578547A1A565C476DEF1716A97B" xlink:to="loc_us-gaap_CorporateNonSegmentMember_051262BC937A6E6371216DEF1716B75F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_359297F853E7FA4B16536E22503E4273" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4768BB4016DC4CE34BAD6DEF171621FD" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_359297F853E7FA4B16536E22503E4273" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_5CC9B37DDDC6CAE464B16DEF17160BD3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4768BB4016DC4CE34BAD6DEF171621FD" xlink:to="loc_us-gaap_CostOfRevenue_5CC9B37DDDC6CAE464B16DEF17160BD3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaap_SellingAndMarketingExpense_1AEB0D34DFC5F270AA8F6DEF17176774" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4768BB4016DC4CE34BAD6DEF171621FD" xlink:to="loc_us-gaap_SellingAndMarketingExpense_1AEB0D34DFC5F270AA8F6DEF17176774" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AmortizationNonproduction" xlink:label="loc_lpsn_AmortizationNonproduction_5B904FADCDE7A550461D6E1B0432FC40" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4768BB4016DC4CE34BAD6DEF171621FD" xlink:to="loc_lpsn_AmortizationNonproduction_5B904FADCDE7A550461D6E1B0432FC40" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_SegmentReportingUnallocatedCorporateExpenses" xlink:label="loc_lpsn_SegmentReportingUnallocatedCorporateExpenses_D8FE37089CD815ADB4A76DEF171798B1" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4768BB4016DC4CE34BAD6DEF171621FD" xlink:to="loc_lpsn_SegmentReportingUnallocatedCorporateExpenses_D8FE37089CD815ADB4A76DEF171798B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_F68977E2A83B67FCAEC96DEF17175740" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4768BB4016DC4CE34BAD6DEF171621FD" xlink:to="loc_us-gaap_OperatingIncomeLoss_F68977E2A83B67FCAEC96DEF17175740" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/SegmentInformationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquity" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F4C1804C5A8553CC87946DEF16596996" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F4C1804C5A8553CC87946DEF16596996" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_0C8AB378E7E0DF7E7DA86DEF165ACA0E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F4C1804C5A8553CC87946DEF16596996" xlink:to="loc_us-gaap_AwardTypeAxis_0C8AB378E7E0DF7E7DA86DEF165ACA0E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EB86A70E4EB0834F9E7C6DEF165A1E5E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0C8AB378E7E0DF7E7DA86DEF165ACA0E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EB86A70E4EB0834F9E7C6DEF165A1E5E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EB86A70E4EB0834F9E7C6DEF165A1E5E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0C8AB378E7E0DF7E7DA86DEF165ACA0E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EB86A70E4EB0834F9E7C6DEF165A1E5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_7222FD96926F200E17BB6DEF165A4DC9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EB86A70E4EB0834F9E7C6DEF165A1E5E" xlink:to="loc_us-gaap_EmployeeStockOptionMember_7222FD96926F200E17BB6DEF165A4DC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_D42AF4A78394C914BB6E6DEF165B7D3D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_EB86A70E4EB0834F9E7C6DEF165A1E5E" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_D42AF4A78394C914BB6E6DEF165B7D3D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_0BA34E60D244E7AAE9EB6DEF165B30DF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F4C1804C5A8553CC87946DEF16596996" xlink:to="loc_us-gaap_PlanNameAxis_0BA34E60D244E7AAE9EB6DEF165B30DF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_0BA34E60D244E7AAE9EB6DEF165B30DF" xlink:to="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_0BA34E60D244E7AAE9EB6DEF165B30DF" xlink:to="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_NineteenNinetyEightPlanMember" xlink:label="loc_lpsn_NineteenNinetyEightPlanMember_C7DABC5DCC23ECB0162E6DEF165B62E5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:to="loc_lpsn_NineteenNinetyEightPlanMember_C7DABC5DCC23ECB0162E6DEF165B62E5" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TwoThousandPlanMember" xlink:label="loc_lpsn_TwoThousandPlanMember_BD420E6792C0F7CD13066DEF165CE553" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:to="loc_lpsn_TwoThousandPlanMember_BD420E6792C0F7CD13066DEF165CE553" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TwoThousandNinePlanMember" xlink:label="loc_lpsn_TwoThousandNinePlanMember_37EB2FC8DFA1D425D43A6DEF165C0B86" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:to="loc_lpsn_TwoThousandNinePlanMember_37EB2FC8DFA1D425D43A6DEF165C0B86" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TwoThousandNinePlanAmendedMember" xlink:label="loc_lpsn_TwoThousandNinePlanAmendedMember_7B08DCAA5BABFF2C2FA26DEF165C67C4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:to="loc_lpsn_TwoThousandNinePlanAmendedMember_7B08DCAA5BABFF2C2FA26DEF165C67C4" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TwoThousandTenEmployeeStockPurchasePlanMember" xlink:label="loc_lpsn_TwoThousandTenEmployeeStockPurchasePlanMember_12078A5B616DDD16ED5F6DEF165C6712" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:to="loc_lpsn_TwoThousandTenEmployeeStockPurchasePlanMember_12078A5B616DDD16ED5F6DEF165C6712" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AmendedAndRestated2010EmployeeStockPurchasePlanMember" xlink:label="loc_lpsn_AmendedAndRestated2010EmployeeStockPurchasePlanMember_9DB83237EB24EF8705E06DEF165D2575" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:to="loc_lpsn_AmendedAndRestated2010EmployeeStockPurchasePlanMember_9DB83237EB24EF8705E06DEF165D2575" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_TwoThousandNineteenEmployeeStockPurchasePlanMember" xlink:label="loc_lpsn_TwoThousandNineteenEmployeeStockPurchasePlanMember_F9FBB4789609F8C560476E687FD031B3" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:to="loc_lpsn_TwoThousandNineteenEmployeeStockPurchasePlanMember_F9FBB4789609F8C560476E687FD031B3" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_A2018PlanMember" xlink:label="loc_lpsn_A2018PlanMember_1EB2446F19062DAF92336DEF165DDCBD" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_4D9F29C44CA8C4E4D9736DEF165B2DEE" xlink:to="loc_lpsn_A2018PlanMember_1EB2446F19062DAF92336DEF165DDCBD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_7303951624D31771F7FA6E6A23A1B447" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_F4C1804C5A8553CC87946DEF16596996" xlink:to="loc_srt_RangeAxis_7303951624D31771F7FA6E6A23A1B447" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_1A637EDC73E89035C0826E6A23A39E15_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7303951624D31771F7FA6E6A23A1B447" xlink:to="loc_srt_RangeMember_1A637EDC73E89035C0826E6A23A39E15_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_1A637EDC73E89035C0826E6A23A39E15" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7303951624D31771F7FA6E6A23A1B447" xlink:to="loc_srt_RangeMember_1A637EDC73E89035C0826E6A23A39E15" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_792939A2F4E777F3739B6E6A48B3D989" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1A637EDC73E89035C0826E6A23A39E15" xlink:to="loc_srt_MinimumMember_792939A2F4E777F3739B6E6A48B3D989" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_C396CB1B2178864972B36E6A7BA2BFFA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1A637EDC73E89035C0826E6A23A39E15" xlink:to="loc_srt_MaximumMember_C396CB1B2178864972B36E6A7BA2BFFA" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_CommonStockIncreaseInSharesAuthorizedDuringThePeriod" xlink:label="loc_lpsn_CommonStockIncreaseInSharesAuthorizedDuringThePeriod_331FDB27DAB3A16FFF046E5A5BF32465" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_lpsn_CommonStockIncreaseInSharesAuthorizedDuringThePeriod_331FDB27DAB3A16FFF046E5A5BF32465" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_7BA2A28425006487542E6DEF165D05CE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_7BA2A28425006487542E6DEF165D05CE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_CEB3238D989943249B6C6DEF165D3A7B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_CommonStockSharesIssued_CEB3238D989943249B6C6DEF165D3A7B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_B7CB05771B0699D6D5D36DEF165ED6A0" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_B7CB05771B0699D6D5D36DEF165ED6A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_B7B899D90A688C4D03F46DEF165EE2BB" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_B7B899D90A688C4D03F46DEF165EE2BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_607E2B5C9D1041E2158D6DEF165E2E5A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_607E2B5C9D1041E2158D6DEF165E2E5A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_680C940383328C949B226DEF165E631D" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_PreferredStockSharesIssued_680C940383328C949B226DEF165E631D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_4C7468E2DC50B4BDFFE56DEF165E0F2C" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_4C7468E2DC50B4BDFFE56DEF165E0F2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_14F0C8AEA8BC8CF5D4E86DEF165F2B59" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_14F0C8AEA8BC8CF5D4E86DEF165F2B59" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_76EC43835054B6A819CE6DEF165F8C7F" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_76EC43835054B6A819CE6DEF165F8C7F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_4197A661AD03D64180E66DEF165FF847" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_4197A661AD03D64180E66DEF165FF847" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_221C3DB542B7D6A057B66DEF165F5F00" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_221C3DB542B7D6A057B66DEF165F5F00" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPeriodUsedToDetermineVolatility" xlink:label="loc_lpsn_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPeriodUsedToDetermineVolatility_5F3EE61C543DD352B0906DEF165F0790" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_lpsn_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPeriodUsedToDetermineVolatility_5F3EE61C543DD352B0906DEF165F0790" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_5FB9DCD6993811F6765E6DEF165FE9DD" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_5FB9DCD6993811F6765E6DEF165FE9DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_823AF727CBFF2B9D3BB36DEF165F9D78" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_823AF727CBFF2B9D3BB36DEF165F9D78" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_A726040CFA4ACD9C875D6DEF16601E89" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_A726040CFA4ACD9C875D6DEF16601E89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_353D761CA8F85BE459316DEF1660215F" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_353D761CA8F85BE459316DEF1660215F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_B0922EA8198D5F1C3A036DEF1660E8A6" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_B0922EA8198D5F1C3A036DEF1660E8A6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_0B0835AB1EF83508EEC76DEF16603FA1" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_0B0835AB1EF83508EEC76DEF16603FA1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_D3F513FEDA7110B654126DEF16603BA7" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_D3F513FEDA7110B654126DEF16603BA7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_04AF5A47C5365C885BB06DEF1661A195" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_04AF5A47C5365C885BB06DEF1661A195" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_E690B5979D8822E5F1646DEF16616149" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_E690B5979D8822E5F1646DEF16616149" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_20DCB7C9143C8684915E6DEF16619A21" xlink:type="locator" />
    <link:definitionArc order="23" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_us-gaap_ShareBasedCompensation_20DCB7C9143C8684915E6DEF16619A21" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_AccrualForCashAwardsToBeSettledInShares" xlink:label="loc_lpsn_AccrualForCashAwardsToBeSettledInShares_0669B41DABBB8F1916F36E6FAA53C14A" xlink:type="locator" />
    <link:definitionArc order="24" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E81BCDF95B6FBB4AB8E6DEF165DE32C" xlink:to="loc_lpsn_AccrualForCashAwardsToBeSettledInShares_0669B41DABBB8F1916F36E6FAA53C14A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquitySummaryOfOutstandingAndVestedOptionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_2669524F40D0E228288C663FD99C27B9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_2669524F40D0E228288C663FD99C27B9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_66E125422B33AAE9A824663FD99C098C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_2669524F40D0E228288C663FD99C27B9" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_66E125422B33AAE9A824663FD99C098C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_66E125422B33AAE9A824663FD99C098C" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_66E125422B33AAE9A824663FD99C098C" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeOneMember" xlink:label="loc_lpsn_ExercisePriceRangeOneMember_A8BDBB5F5D6572FC009F663FD99CF1CD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeOneMember_A8BDBB5F5D6572FC009F663FD99CF1CD" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeTwoMember" xlink:label="loc_lpsn_ExercisePriceRangeTwoMember_8E9DFAA02210FF8E4E05663FD99D95D5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeTwoMember_8E9DFAA02210FF8E4E05663FD99D95D5" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeThreeMember" xlink:label="loc_lpsn_ExercisePriceRangeThreeMember_D840DA4986D5A0BF3542663FD99D46CB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeThreeMember_D840DA4986D5A0BF3542663FD99D46CB" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeFourMember" xlink:label="loc_lpsn_ExercisePriceRangeFourMember_5DA8EEE58CC4D9038D6C663FD99D60D2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeFourMember_5DA8EEE58CC4D9038D6C663FD99D60D2" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeFiveMember" xlink:label="loc_lpsn_ExercisePriceRangeFiveMember_9B12681CEA03714751E5663FD99DA3F3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeFiveMember_9B12681CEA03714751E5663FD99DA3F3" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeSixMember" xlink:label="loc_lpsn_ExercisePriceRangeSixMember_BF154BE20ACC5D06FFC3663FD99D042D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeSixMember_BF154BE20ACC5D06FFC3663FD99D042D" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeSevenMember" xlink:label="loc_lpsn_ExercisePriceRangeSevenMember_5988FB7310C3738BF7A9663FD99D6704" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeSevenMember_5988FB7310C3738BF7A9663FD99D6704" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeEightMember" xlink:label="loc_lpsn_ExercisePriceRangeEightMember_48227EBB0146F843E2CE663FD99EC20B" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeEightMember_48227EBB0146F843E2CE663FD99EC20B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeNineMember" xlink:label="loc_lpsn_ExercisePriceRangeNineMember_C212151B5B0B6E5DE980663FD99E8E8C" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeNineMember_C212151B5B0B6E5DE980663FD99E8E8C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_ExercisePriceRangeTenMember" xlink:label="loc_lpsn_ExercisePriceRangeTenMember_FC268724E98D5AB08CAD663FD99EED5B" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_9E7F7F793701290FB097663FD99CA71C" xlink:to="loc_lpsn_ExercisePriceRangeTenMember_FC268724E98D5AB08CAD663FD99EED5B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_4B29D46F941EFE2C561A663FD99EA0F0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_4B29D46F941EFE2C561A663FD99EA0F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_1513D6898BBE21FDCED5663FD99EEFDC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_1513D6898BBE21FDCED5663FD99EEFDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_FA816D543F4055257711663FD99FB95C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_FA816D543F4055257711663FD99FB95C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_F87D032244027BD154DB663FD99FF285" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_F87D032244027BD154DB663FD99FF285" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_7DDD9871FEA169A05985663FD99FFA6C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_7DDD9871FEA169A05985663FD99FFA6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_ECDF1C6669AC887F6528663FD99F23EE" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_ECDF1C6669AC887F6528663FD99F23EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_2E3231AF55FAB8C17793663FD99FF973" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_71EC54540D1257C213AB663FD99EA600" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_2E3231AF55FAB8C17793663FD99FF973" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquitySummaryOfRestrictedStockUnitActivityDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CF7E931CC435AE9FA0F7663FD992E5CE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9D9B39387A614843360D663FD990E384" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CF7E931CC435AE9FA0F7663FD992E5CE" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9D9B39387A614843360D663FD990E384" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_73E88A73E3D62D35BA52663FD991A51B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9D9B39387A614843360D663FD990E384" xlink:to="loc_us-gaap_AwardTypeAxis_73E88A73E3D62D35BA52663FD991A51B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AA4C567BDD70EDE88631663FD99103D2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_73E88A73E3D62D35BA52663FD991A51B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AA4C567BDD70EDE88631663FD99103D2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AA4C567BDD70EDE88631663FD99103D2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_73E88A73E3D62D35BA52663FD991A51B" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AA4C567BDD70EDE88631663FD99103D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_00377D67F17F6D96B01A663FD991D5F5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_AA4C567BDD70EDE88631663FD99103D2" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_00377D67F17F6D96B01A663FD991D5F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6BC518CE7FEBCAFD97D0663FD9925233" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CF7E931CC435AE9FA0F7663FD992E5CE" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6BC518CE7FEBCAFD97D0663FD9925233" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_54133256612C23893F2F663FD9920950" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6BC518CE7FEBCAFD97D0663FD9925233" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_54133256612C23893F2F663FD9920950" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0E5AD54FE36427355A83663FD992FACF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6BC518CE7FEBCAFD97D0663FD9925233" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0E5AD54FE36427355A83663FD992FACF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_CBC2A2B9575209919BD5663FD9927376" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6BC518CE7FEBCAFD97D0663FD9925233" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_CBC2A2B9575209919BD5663FD9927376" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_E02339E09497407BD614663FD993AB57" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6BC518CE7FEBCAFD97D0663FD9925233" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_E02339E09497407BD614663FD993AB57" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExpectedToVestNumber" xlink:label="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExpectedToVestNumber_C7B58AC8AC4EBE9C5CA3663FD99320B8" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_6BC518CE7FEBCAFD97D0663FD9925233" xlink:to="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExpectedToVestNumber_C7B58AC8AC4EBE9C5CA3663FD99320B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_A74A8BFE8F70189616B2663FD9933DDC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CF7E931CC435AE9FA0F7663FD992E5CE" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_A74A8BFE8F70189616B2663FD9933DDC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_30BE5F27C95F967322CE663FD993B5BD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_A74A8BFE8F70189616B2663FD9933DDC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_30BE5F27C95F967322CE663FD993B5BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_3C0F89A5BD30588C1DAB663FD994D2F3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_A74A8BFE8F70189616B2663FD9933DDC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_3C0F89A5BD30588C1DAB663FD994D2F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_FA1F578E95A517B91F14663FD9944EFA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_A74A8BFE8F70189616B2663FD9933DDC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_FA1F578E95A517B91F14663FD9944EFA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_D96337EE79B7E12896F5663FD99480FA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_A74A8BFE8F70189616B2663FD9933DDC" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_D96337EE79B7E12896F5663FD99480FA" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExpectedToVestWeightedAverageGrantDateFairValue" xlink:label="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExpectedToVestWeightedAverageGrantDateFairValue_0DB7CA88CD318F849A7F663FD9945E6A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_A74A8BFE8F70189616B2663FD9933DDC" xlink:to="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExpectedToVestWeightedAverageGrantDateFairValue_0DB7CA88CD318F849A7F663FD9945E6A" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueAbstract" xlink:label="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueAbstract_52FD987D8E7D7F79DF05663FD995170E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_CF7E931CC435AE9FA0F7663FD992E5CE" xlink:to="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueAbstract_52FD987D8E7D7F79DF05663FD995170E" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueNonvested" xlink:label="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueNonvested_8781EE27B843243A0242663FD995965B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueAbstract_52FD987D8E7D7F79DF05663FD995170E" xlink:to="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueNonvested_8781EE27B843243A0242663FD995965B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20191231.xsd#lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueExpectedToVest" xlink:label="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueExpectedToVest_4C1224B633A25F830DBD663FD995CBDD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueAbstract_52FD987D8E7D7F79DF05663FD995170E" xlink:to="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsAggregateFairValueExpectedToVest_4C1224B633A25F830DBD663FD995CBDD" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquitySummaryOfStockOptionActivityAndWeightedAverageExercisePricesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquityTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquityWeightedAverageAssumptionsOfFairValueOptionsUsingBlackScholesOptionPricingModelDetails" xlink:type="extended" />
</link:linkbase>
