<?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/AccruedExpensesAndOtherCurrentLiabilities" xlink:href="lpsn-20170630.xsd#AccruedExpensesAndOtherCurrentLiabilities" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/AccruedExpensesAndOtherCurrentLiabilitiesDetails" xlink:href="lpsn-20170630.xsd#AccruedExpensesAndOtherCurrentLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/AccruedExpensesAndOtherCurrentLiabilitiesTables" xlink:href="lpsn-20170630.xsd#AccruedExpensesAndOtherCurrentLiabilitiesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CommitmentsAndContingencies" xlink:href="lpsn-20170630.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CommitmentsAndContingenciesDetails" xlink:href="lpsn-20170630.xsd#CommitmentsAndContingenciesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:href="lpsn-20170630.xsd#CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:href="lpsn-20170630.xsd#CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:href="lpsn-20170630.xsd#CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CondensedConsolidatedStatementsOfComprehensiveLossUnaudited" xlink:href="lpsn-20170630.xsd#CondensedConsolidatedStatementsOfComprehensiveLossUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:href="lpsn-20170630.xsd#CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndBasisOfPresentation" xlink:href="lpsn-20170630.xsd#DescriptionOfBusinessAndBasisOfPresentation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DescriptionOfBusinessAndBasisOfPresentationPolicies" xlink:href="lpsn-20170630.xsd#DescriptionOfBusinessAndBasisOfPresentationPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/DocumentAndEntityInformation" xlink:href="lpsn-20170630.xsd#DocumentAndEntityInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurements" xlink:href="lpsn-20170630.xsd#FairValueMeasurements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsDerivativeFinancialInstrumentsDetails" xlink:href="lpsn-20170630.xsd#FairValueMeasurementsDerivativeFinancialInstrumentsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsFinancialAssetsAndLiabilitiesDetails" xlink:href="lpsn-20170630.xsd#FairValueMeasurementsFinancialAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsLevel3LiabilitiesDetails" xlink:href="lpsn-20170630.xsd#FairValueMeasurementsLevel3LiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/FairValueMeasurementsTables" xlink:href="lpsn-20170630.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssets" xlink:href="lpsn-20170630.xsd#GoodwillAndIntangibleAssets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsChangesInCarryingAmountOfGoodwillDetails" xlink:href="lpsn-20170630.xsd#GoodwillAndIntangibleAssetsChangesInCarryingAmountOfGoodwillDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsFutureAmortizationExpenseDetails" xlink:href="lpsn-20170630.xsd#GoodwillAndIntangibleAssetsFutureAmortizationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsNarrativeDetails" xlink:href="lpsn-20170630.xsd#GoodwillAndIntangibleAssetsNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails" xlink:href="lpsn-20170630.xsd#GoodwillAndIntangibleAssetsSummaryOfIntangibleAssetsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsTables" xlink:href="lpsn-20170630.xsd#GoodwillAndIntangibleAssetsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/LegalMatters" xlink:href="lpsn-20170630.xsd#LegalMatters" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/NetLossPerShare" xlink:href="lpsn-20170630.xsd#NetLossPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/NetLossPerShareNarrativeDetails" xlink:href="lpsn-20170630.xsd#NetLossPerShareNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/NetLossPerShareReconciliationOfSharesUsedInCalculatingBasicAndDilutedEarningsPerShareDetails" xlink:href="lpsn-20170630.xsd#NetLossPerShareReconciliationOfSharesUsedInCalculatingBasicAndDilutedEarningsPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/NetLossPerShareTables" xlink:href="lpsn-20170630.xsd#NetLossPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/PropertyAndEquipment" xlink:href="lpsn-20170630.xsd#PropertyAndEquipment" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/PropertyAndEquipmentDetails" xlink:href="lpsn-20170630.xsd#PropertyAndEquipmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/PropertyAndEquipmentTables" xlink:href="lpsn-20170630.xsd#PropertyAndEquipmentTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/Restructuring" xlink:href="lpsn-20170630.xsd#Restructuring" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringNarrativeDetails" xlink:href="lpsn-20170630.xsd#RestructuringNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringRestructuringExpenseDetails" xlink:href="lpsn-20170630.xsd#RestructuringRestructuringExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringRestructuringLiabilityDetails" xlink:href="lpsn-20170630.xsd#RestructuringRestructuringLiabilityDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RestructuringTables" xlink:href="lpsn-20170630.xsd#RestructuringTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RevenueRecognition" xlink:href="lpsn-20170630.xsd#RevenueRecognition" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/RevenueRecognitionDetails" xlink:href="lpsn-20170630.xsd#RevenueRecognitionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformation" xlink:href="lpsn-20170630.xsd#SegmentInformation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationLongLivedAssetsByGeographicRegionDetails" xlink:href="lpsn-20170630.xsd#SegmentInformationLongLivedAssetsByGeographicRegionDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationNarrativeDetails" xlink:href="lpsn-20170630.xsd#SegmentInformationNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationRevenuesAttributableToDomesticAndForeignOperationsDetails" xlink:href="lpsn-20170630.xsd#SegmentInformationRevenuesAttributableToDomesticAndForeignOperationsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationSummaryOfFinancialInformationBySegmentDetails" xlink:href="lpsn-20170630.xsd#SegmentInformationSummaryOfFinancialInformationBySegmentDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/SegmentInformationTables" xlink:href="lpsn-20170630.xsd#SegmentInformationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquity" xlink:href="lpsn-20170630.xsd#StockholdersEquity" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquityNarrativeDetails" xlink:href="lpsn-20170630.xsd#StockholdersEquityNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquitySummaryOfOptionsByRangeOfExercisePricesDetails" xlink:href="lpsn-20170630.xsd#StockholdersEquitySummaryOfOptionsByRangeOfExercisePricesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquitySummaryOfRestrictedStockUnitActivityAndWeightedAverageExercisePriceDetails" xlink:href="lpsn-20170630.xsd#StockholdersEquitySummaryOfRestrictedStockUnitActivityAndWeightedAverageExercisePriceDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquitySummaryOfStockOptionActivityAndWeightedAverageExercisePricesDetails" xlink:href="lpsn-20170630.xsd#StockholdersEquitySummaryOfStockOptionActivityAndWeightedAverageExercisePricesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquityTables" xlink:href="lpsn-20170630.xsd#StockholdersEquityTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.liveperson.com/role/StockholdersEquityWeightedAverageAssumptionsOfFairValueOptionsUsingBlackScholesOptionPricingModelDetails" xlink:href="lpsn-20170630.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/AccruedExpensesAndOtherCurrentLiabilities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/AccruedExpensesAndOtherCurrentLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/AccruedExpensesAndOtherCurrentLiabilitiesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CommitmentsAndContingenciesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_70F80EB70BE79A793DAC80F28DF3FEE4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_72CDCFF8461411A5F88D80F28DF2BE82" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_70F80EB70BE79A793DAC80F28DF3FEE4" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_72CDCFF8461411A5F88D80F28DF2BE82" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_7B2084CB5571A86CC97E80F28DF21C45" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_72CDCFF8461411A5F88D80F28DF2BE82" xlink:to="loc_us-gaap_CreditFacilityAxis_7B2084CB5571A86CC97E80F28DF21C45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_223D3B2B763AC7CAC1C880F28DF266F0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_7B2084CB5571A86CC97E80F28DF21C45" xlink:to="loc_us-gaap_CreditFacilityDomain_223D3B2B763AC7CAC1C880F28DF266F0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_223D3B2B763AC7CAC1C880F28DF266F0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_7B2084CB5571A86CC97E80F28DF21C45" xlink:to="loc_us-gaap_CreditFacilityDomain_223D3B2B763AC7CAC1C880F28DF266F0" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_LetterOfCreditForOfficeSpaceMember" xlink:label="loc_lpsn_LetterOfCreditForOfficeSpaceMember_C5F81CC6762F01B8DA3F80F28DF20D51" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_223D3B2B763AC7CAC1C880F28DF266F0" xlink:to="loc_lpsn_LetterOfCreditForOfficeSpaceMember_C5F81CC6762F01B8DA3F80F28DF20D51" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_LetterOfCreditForSecurityDepositMember" xlink:label="loc_lpsn_LetterOfCreditForSecurityDepositMember_622AFBBA4D78D0E1008180F28DF2D8FB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_223D3B2B763AC7CAC1C880F28DF266F0" xlink:to="loc_lpsn_LetterOfCreditForSecurityDepositMember_622AFBBA4D78D0E1008180F28DF2D8FB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_DD6DCDC40D42047153B180F28DF22D23" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_72CDCFF8461411A5F88D80F28DF2BE82" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_DD6DCDC40D42047153B180F28DF22D23" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_017FFF062B239FA7BDD680F28DF3DD9A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_DD6DCDC40D42047153B180F28DF22D23" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_017FFF062B239FA7BDD680F28DF3DD9A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_017FFF062B239FA7BDD680F28DF3DD9A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_DD6DCDC40D42047153B180F28DF22D23" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_017FFF062B239FA7BDD680F28DF3DD9A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCreditMember" xlink:label="loc_us-gaap_LineOfCreditMember_684F6448722D0242CAA880F28DF3B3E4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_017FFF062B239FA7BDD680F28DF3DD9A" xlink:to="loc_us-gaap_LineOfCreditMember_684F6448722D0242CAA880F28DF3B3E4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_CA59165BCEB56AAADC6580F28DF37316" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_70F80EB70BE79A793DAC80F28DF3FEE4" xlink:to="loc_us-gaap_LineOfCredit_CA59165BCEB56AAADC6580F28DF37316" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CondensedConsolidatedBalanceSheetsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CondensedConsolidatedBalanceSheetsUnauditedParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CondensedConsolidatedStatementsOfComprehensiveLossUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/CondensedConsolidatedStatementsOfOperationsUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_15AB908EA27A8A0B7E417AA363913C7E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_StatementTable_15AB908EA27A8A0B7E417AA363913C7E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_147CA1FC87839A3B948D7AA36392C895" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_15AB908EA27A8A0B7E417AA363913C7E" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_147CA1FC87839A3B948D7AA36392C895" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1905F6AC29D3AE808D5A7AA36392D48D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_147CA1FC87839A3B948D7AA36392C895" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1905F6AC29D3AE808D5A7AA36392D48D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_1905F6AC29D3AE808D5A7AA36392D48D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_147CA1FC87839A3B948D7AA36392C895" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_1905F6AC29D3AE808D5A7AA36392D48D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_6F91F4DED5207AF3F7947AA36392AF74" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1905F6AC29D3AE808D5A7AA36392D48D" xlink:to="loc_us-gaap_CostOfSalesMember_6F91F4DED5207AF3F7947AA36392AF74" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SellingAndMarketingExpenseMember" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_8A51895DDBE101BFC41B7AA363920FF6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1905F6AC29D3AE808D5A7AA36392D48D" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_8A51895DDBE101BFC41B7AA363920FF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_1359D43826874A3356807AA36392BA68" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1905F6AC29D3AE808D5A7AA36392D48D" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_1359D43826874A3356807AA36392BA68" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_FCE46D2D0077A50C4C087AA36392E71F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_1905F6AC29D3AE808D5A7AA36392D48D" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_FCE46D2D0077A50C4C087AA36392E71F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_990A0195941588D6BB797AA363A6B9B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_Revenues_990A0195941588D6BB797AA363A6B9B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostsAndExpensesAbstract" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_474D50B42807F59FD4D77AA363A612D3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:to="loc_us-gaap_CostOfRevenue_474D50B42807F59FD4D77AA363A612D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaap_SellingAndMarketingExpense_BA05568E143AE451CFDA7AA363A606DD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:to="loc_us-gaap_SellingAndMarketingExpense_BA05568E143AE451CFDA7AA363A606DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_53ADC4D34B00853FA2F37AA363A6167A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_53ADC4D34B00853FA2F37AA363A6167A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_031EC0D4947BA81273567AA363A6DA89" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_031EC0D4947BA81273567AA363A6DA89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_3CA135515F59AE1CBB247AA363A7D519" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:to="loc_us-gaap_RestructuringCharges_3CA135515F59AE1CBB247AA363A7D519" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_C8B02145AAEBF74BE1247AA363A704B3" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_C8B02145AAEBF74BE1247AA363A704B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostsAndExpenses" xlink:label="loc_us-gaap_CostsAndExpenses_27E8B8D253CEF6BB45F27AA363A787F6" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_738FD5F06C3A04FD73497AA363A66E89" xlink:to="loc_us-gaap_CostsAndExpenses_27E8B8D253CEF6BB45F27AA363A787F6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_93D4FF26733B9653904D7AA363A7BB37" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_OperatingIncomeLoss_93D4FF26733B9653904D7AA363A7BB37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_11D398A09E8C736131DA7AA363A7127F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_11D398A09E8C736131DA7AA363A7127F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_198281E47E070189E2557AA363A70168" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_198281E47E070189E2557AA363A70168" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_D0BE8BB9CF0A342EF7B27AA363A729C0" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_D0BE8BB9CF0A342EF7B27AA363A729C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_A02DD207AA68273855D67AA363A8F43F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_NetIncomeLoss_A02DD207AA68273855D67AA363A8F43F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaap_ShareBasedCompensation_34DE5B42EA55A80FC0FF7AA363A86C16" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_ShareBasedCompensation_34DE5B42EA55A80FC0FF7AA363A86C16" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DepreciationNonproduction" xlink:label="loc_us-gaap_DepreciationNonproduction_3EE72422FBABD70018487AA363A82563" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_DepreciationNonproduction_3EE72422FBABD70018487AA363A82563" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_AF1020EBEA16D49368807AA363A85386" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_EarningsPerShareAbstract_AF1020EBEA16D49368807AA363A85386" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_F3E5ED7EF409346608F27AA363A84EE8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_AF1020EBEA16D49368807AA363A85386" xlink:to="loc_us-gaap_EarningsPerShareBasic_F3E5ED7EF409346608F27AA363A84EE8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_D0B84CF90A4B0A8377297AA363A8CFF5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_AF1020EBEA16D49368807AA363A85386" xlink:to="loc_us-gaap_EarningsPerShareDiluted_D0B84CF90A4B0A8377297AA363A8CFF5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_6D9829C38D79EB1B0E007AA363A802E9" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_84B7BAD5E4208754FB017AA363A55FE9" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_6D9829C38D79EB1B0E007AA363A802E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_0E3854E1AA5DD41ED1FB7AA363A9A073" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_6D9829C38D79EB1B0E007AA363A802E9" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_0E3854E1AA5DD41ED1FB7AA363A9A073" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_667EC9A02DDFD06666377AA363A97455" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_6D9829C38D79EB1B0E007AA363A802E9" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_667EC9A02DDFD06666377AA363A97455" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndBasisOfPresentation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DescriptionOfBusinessAndBasisOfPresentationPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/DocumentAndEntityInformation" 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/FairValueMeasurementsDerivativeFinancialInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_DD75D2F9B1191D33F21280B3D645C2B1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_7B8118A6D96ECDC5431480B3D6452B04" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_DD75D2F9B1191D33F21280B3D645C2B1" xlink:to="loc_us-gaap_DerivativeTable_7B8118A6D96ECDC5431480B3D6452B04" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_1214EFF86D7BED43F11480B3D6458D41" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_7B8118A6D96ECDC5431480B3D6452B04" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_1214EFF86D7BED43F11480B3D6458D41" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_F2E4F1BBCF8F3A69BDE280B3D645E4ED_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_1214EFF86D7BED43F11480B3D6458D41" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_F2E4F1BBCF8F3A69BDE280B3D645E4ED_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_F2E4F1BBCF8F3A69BDE280B3D645E4ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_1214EFF86D7BED43F11480B3D6458D41" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_F2E4F1BBCF8F3A69BDE280B3D645E4ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="loc_us-gaap_ForeignExchangeContractMember_1AC0D161E204408EECFF80B3D6451E27" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_F2E4F1BBCF8F3A69BDE280B3D645E4ED" xlink:to="loc_us-gaap_ForeignExchangeContractMember_1AC0D161E204408EECFF80B3D6451E27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_4CA9E63B51AE3864F6C480B3D645571B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_7B8118A6D96ECDC5431480B3D6452B04" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_4CA9E63B51AE3864F6C480B3D645571B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3CBDCFDD3773288C434080B3D64533F2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_4CA9E63B51AE3864F6C480B3D645571B" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3CBDCFDD3773288C434080B3D64533F2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3CBDCFDD3773288C434080B3D64533F2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_4CA9E63B51AE3864F6C480B3D645571B" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3CBDCFDD3773288C434080B3D64533F2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeFinancialInstrumentsAssetsMember" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsAssetsMember_1B29F0090C5659133D6680B5EA272A27" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_3CBDCFDD3773288C434080B3D64533F2" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsAssetsMember_1B29F0090C5659133D6680B5EA272A27" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_0F1B7FD889E628C4A59280B641D7EC9C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_7B8118A6D96ECDC5431480B3D6452B04" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_0F1B7FD889E628C4A59280B641D7EC9C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F8F975764A5D7888C9AC80B641D76328_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_0F1B7FD889E628C4A59280B641D7EC9C" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F8F975764A5D7888C9AC80B641D76328_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F8F975764A5D7888C9AC80B641D76328" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_0F1B7FD889E628C4A59280B641D7EC9C" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F8F975764A5D7888C9AC80B641D76328" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_2A79C0DC8BECE17FDFE880B68DBF32AF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_F8F975764A5D7888C9AC80B641D76328" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_2A79C0DC8BECE17FDFE880B68DBF32AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_763E3585000A6243AEB780B3D645ED4D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_7B8118A6D96ECDC5431480B3D6452B04" xlink:to="loc_us-gaap_HedgingDesignationAxis_763E3585000A6243AEB780B3D645ED4D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_CBA9586EC2297F6BA57780B3D6450895_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_763E3585000A6243AEB780B3D645ED4D" xlink:to="loc_us-gaap_HedgingDesignationDomain_CBA9586EC2297F6BA57780B3D6450895_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_CBA9586EC2297F6BA57780B3D6450895" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_763E3585000A6243AEB780B3D645ED4D" xlink:to="loc_us-gaap_HedgingDesignationDomain_CBA9586EC2297F6BA57780B3D6450895" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NondesignatedMember" xlink:label="loc_us-gaap_NondesignatedMember_900BAA6279AFB81A8C3180B3D645A717" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_CBA9586EC2297F6BA57780B3D6450895" xlink:to="loc_us-gaap_NondesignatedMember_900BAA6279AFB81A8C3180B3D645A717" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_BE08E15D233609CAE0F780B3D64529C9" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_7B8118A6D96ECDC5431480B3D6452B04" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_BE08E15D233609CAE0F780B3D64529C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_7B44F2651B905E0073E480B3D6453421_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_BE08E15D233609CAE0F780B3D64529C9" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_7B44F2651B905E0073E480B3D6453421_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_7B44F2651B905E0073E480B3D6453421" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_BE08E15D233609CAE0F780B3D64529C9" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_7B44F2651B905E0073E480B3D6453421" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember" xlink:label="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_7EA657866FD2B387130F80B3D645FEF7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_7B44F2651B905E0073E480B3D6453421" xlink:to="loc_us-gaap_PrepaidExpensesAndOtherCurrentAssetsMember_7EA657866FD2B387130F80B3D645FEF7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccruedLiabilitiesMember" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_4233F573CF8DFAB1482280B3D6457491" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_7B44F2651B905E0073E480B3D6453421" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_4233F573CF8DFAB1482280B3D6457491" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_FAD81733757320AB19DC80B3D645DF98" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_7B8118A6D96ECDC5431480B3D6452B04" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_FAD81733757320AB19DC80B3D645DF98" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3BC35926938C91FDF46380B3D645DB8C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_FAD81733757320AB19DC80B3D645DF98" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3BC35926938C91FDF46380B3D645DB8C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_3BC35926938C91FDF46380B3D645DB8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_FAD81733757320AB19DC80B3D645DF98" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_3BC35926938C91FDF46380B3D645DB8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherExpenseMember" xlink:label="loc_us-gaap_OtherExpenseMember_F80A265A1B6335FBECF680B3D645EC54" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_3BC35926938C91FDF46380B3D645DB8C" xlink:to="loc_us-gaap_OtherExpenseMember_F80A265A1B6335FBECF680B3D645EC54" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalents" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalents_13A76A41CF608AC711CE80B3D645F211" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DD75D2F9B1191D33F21280B3D645C2B1" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalents_13A76A41CF608AC711CE80B3D645F211" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_2CC0AE2CD4B8F9614EB380B3D64505C3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DD75D2F9B1191D33F21280B3D645C2B1" xlink:to="loc_invest_DerivativeNotionalAmount_2CC0AE2CD4B8F9614EB380B3D64505C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeFairValueOfDerivativeNet" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeNet_F35820FF211C658A6D9F80B3D645D066" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DD75D2F9B1191D33F21280B3D645C2B1" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeNet_F35820FF211C658A6D9F80B3D645D066" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_A2B37B764EE9C959479780B3D645FD3E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DD75D2F9B1191D33F21280B3D645C2B1" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_A2B37B764EE9C959479780B3D645FD3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_4D3CB4F76ECAEA32AE8680B3D645CF83" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DD75D2F9B1191D33F21280B3D645C2B1" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_4D3CB4F76ECAEA32AE8680B3D645CF83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet_FCB0C9B4C99E4BBA629880B3D645C541" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_DD75D2F9B1191D33F21280B3D645C2B1" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossRecognizedInIncomeIneffectivePortionAndAmountExcludedFromEffectivenessTestingNet_FCB0C9B4C99E4BBA629880B3D645C541" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/FairValueMeasurementsFinancialAssetsAndLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_C3DCA262F1F1891A49A680F28E0A8B2C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_CE631992DBB03045B2B980F28E08784E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_C3DCA262F1F1891A49A680F28E0A8B2C" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_CE631992DBB03045B2B980F28E08784E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3078AFC064AE879EE4DC80F28E08A0AB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_CE631992DBB03045B2B980F28E08784E" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3078AFC064AE879EE4DC80F28E08A0AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_FFE4BC598F55D9B61C6280F28E08019A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3078AFC064AE879EE4DC80F28E08A0AB" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_FFE4BC598F55D9B61C6280F28E08019A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_FFE4BC598F55D9B61C6280F28E08019A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3078AFC064AE879EE4DC80F28E08A0AB" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_FFE4BC598F55D9B61C6280F28E08019A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_32302516DA7429124E9180F28E080261" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_FFE4BC598F55D9B61C6280F28E08019A" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_32302516DA7429124E9180F28E080261" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B5128B605AA05E218B3480F28E0803FD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_CE631992DBB03045B2B980F28E08784E" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B5128B605AA05E218B3480F28E0803FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_937AAFC71EE77C255BE180F28E080780_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B5128B605AA05E218B3480F28E0803FD" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_937AAFC71EE77C255BE180F28E080780_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_937AAFC71EE77C255BE180F28E080780" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_B5128B605AA05E218B3480F28E0803FD" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_937AAFC71EE77C255BE180F28E080780" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_67F58A9F2802C62FF51680F28E081F47" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_937AAFC71EE77C255BE180F28E080780" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_67F58A9F2802C62FF51680F28E081F47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_0AAF62E51EA6A31459D780F28E08C1A4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_937AAFC71EE77C255BE180F28E080780" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_0AAF62E51EA6A31459D780F28E08C1A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_4C60855554044684F4E680F28E09DA2C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_937AAFC71EE77C255BE180F28E080780" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_4C60855554044684F4E680F28E09DA2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByAssetClassAxis" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_EA0B1A30B8355A78422380F28E094902" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_CE631992DBB03045B2B980F28E08784E" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_EA0B1A30B8355A78422380F28E094902" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_F8F605E449738A91CB2A80F28E09A66C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_EA0B1A30B8355A78422380F28E094902" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_F8F605E449738A91CB2A80F28E09A66C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_F8F605E449738A91CB2A80F28E09A66C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_EA0B1A30B8355A78422380F28E094902" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_F8F605E449738A91CB2A80F28E09A66C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MoneyMarketFundsMember" xlink:label="loc_us-gaap_MoneyMarketFundsMember_826AB27271F1BD96D75C80F28E090A05" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_F8F605E449738A91CB2A80F28E09A66C" xlink:to="loc_us-gaap_MoneyMarketFundsMember_826AB27271F1BD96D75C80F28E090A05" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeFinancialInstrumentsAssetsMember" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsAssetsMember_FCABF7F165869DACCFF880F28E09C27B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_F8F605E449738A91CB2A80F28E09A66C" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsAssetsMember_FCABF7F165869DACCFF880F28E09C27B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_6BA834C824E136143FF580F28E096EB3" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_CE631992DBB03045B2B980F28E08784E" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_6BA834C824E136143FF580F28E096EB3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_D4233CEFB0F720F5FCC880F28E09CCCE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_6BA834C824E136143FF580F28E096EB3" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_D4233CEFB0F720F5FCC880F28E09CCCE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_D4233CEFB0F720F5FCC880F28E09CCCE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_6BA834C824E136143FF580F28E096EB3" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_D4233CEFB0F720F5FCC880F28E09CCCE" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ContingentEarnOutMember" xlink:label="loc_lpsn_ContingentEarnOutMember_AE6C23510E467BF0645880F28E09AE75" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_D4233CEFB0F720F5FCC880F28E09CCCE" xlink:to="loc_lpsn_ContingentEarnOutMember_AE6C23510E467BF0645880F28E09AE75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember" xlink:label="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_8A2F2DB821D9BA12505C80F28E0946B1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_D4233CEFB0F720F5FCC880F28E09CCCE" xlink:to="loc_us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember_8A2F2DB821D9BA12505C80F28E0946B1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_06C081FE1860D5721CF180F28E09B347" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_CE631992DBB03045B2B980F28E08784E" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_06C081FE1860D5721CF180F28E09B347" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_972C7A46B01D7C2AD12F80F28E09D281_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_06C081FE1860D5721CF180F28E09B347" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_972C7A46B01D7C2AD12F80F28E09D281_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_972C7A46B01D7C2AD12F80F28E09D281" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_06C081FE1860D5721CF180F28E09B347" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_972C7A46B01D7C2AD12F80F28E09D281" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ForeignExchangeContractMember" xlink:label="loc_us-gaap_ForeignExchangeContractMember_F827AF1B9396678A4FCD80F28E097330" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_972C7A46B01D7C2AD12F80F28E09D281" xlink:to="loc_us-gaap_ForeignExchangeContractMember_F827AF1B9396678A4FCD80F28E097330" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_C2ECE4B55F970CE8B8EE80F28E0AC91B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_C3DCA262F1F1891A49A680F28E0A8B2C" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_C2ECE4B55F970CE8B8EE80F28E0AC91B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_69C95EB357BD4C48B6B780F28E0A69F2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_C3DCA262F1F1891A49A680F28E0A8B2C" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_69C95EB357BD4C48B6B780F28E0A69F2" 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/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6C3FA04DEAD8F812603C7AA362C16927" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_726A163016D019F9AEC37AA362C031BC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6C3FA04DEAD8F812603C7AA362C16927" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_726A163016D019F9AEC37AA362C031BC" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2F1458A1288DAE67AAC87AA362C02941" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_726A163016D019F9AEC37AA362C031BC" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2F1458A1288DAE67AAC87AA362C02941" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_856CA6DFF46F3C99107E7AA362C0F2ED_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2F1458A1288DAE67AAC87AA362C02941" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_856CA6DFF46F3C99107E7AA362C0F2ED_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_856CA6DFF46F3C99107E7AA362C0F2ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_2F1458A1288DAE67AAC87AA362C02941" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_856CA6DFF46F3C99107E7AA362C0F2ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_F2A6A43AFBF49BD6B9937AA362C07CBF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_856CA6DFF46F3C99107E7AA362C0F2ED" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_F2A6A43AFBF49BD6B9937AA362C07CBF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ACCE4B64A6473995170F7AA362C07223" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_726A163016D019F9AEC37AA362C031BC" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ACCE4B64A6473995170F7AA362C07223" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7EFBA1878F0522541D9C7AA362C0601D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ACCE4B64A6473995170F7AA362C07223" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7EFBA1878F0522541D9C7AA362C0601D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7EFBA1878F0522541D9C7AA362C0601D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ACCE4B64A6473995170F7AA362C07223" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7EFBA1878F0522541D9C7AA362C0601D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_BEFEF85D986775E6AEFF7AA362C1F236" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7EFBA1878F0522541D9C7AA362C0601D" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_BEFEF85D986775E6AEFF7AA362C1F236" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_BusinessCombinationContingentConsiderationArrangementsChangeInContingentConsiderationLiabilityRollForward" xlink:label="loc_lpsn_BusinessCombinationContingentConsiderationArrangementsChangeInContingentConsiderationLiabilityRollForward_05905612F75ACC8960E37AA362C1C0B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_6C3FA04DEAD8F812603C7AA362C16927" xlink:to="loc_lpsn_BusinessCombinationContingentConsiderationArrangementsChangeInContingentConsiderationLiabilityRollForward_05905612F75ACC8960E37AA362C1C0B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_B634670E2218E15DCB137AA362C1C4A7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_BusinessCombinationContingentConsiderationArrangementsChangeInContingentConsiderationLiabilityRollForward_05905612F75ACC8960E37AA362C1C0B4" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_B634670E2218E15DCB137AA362C1C4A7" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_BusinessCombinationContingentConsiderationPaymentOfAPortionOfPotentialEarnOutConsiderationAmount" xlink:label="loc_lpsn_BusinessCombinationContingentConsiderationPaymentOfAPortionOfPotentialEarnOutConsiderationAmount_EC32B234A5EC49EAA4517AA362C12B01" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_BusinessCombinationContingentConsiderationArrangementsChangeInContingentConsiderationLiabilityRollForward_05905612F75ACC8960E37AA362C1C0B4" xlink:to="loc_lpsn_BusinessCombinationContingentConsiderationPaymentOfAPortionOfPotentialEarnOutConsiderationAmount_EC32B234A5EC49EAA4517AA362C12B01" 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/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_FDC07EC032A3F84763177AA3630BF9B3" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_0DEFB7DC44F1230084AB7AA3630A6E15" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_FDC07EC032A3F84763177AA3630BF9B3" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_0DEFB7DC44F1230084AB7AA3630A6E15" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_5BBBF4BD85BE66DB48247AA3630AAA87" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_0DEFB7DC44F1230084AB7AA3630A6E15" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_5BBBF4BD85BE66DB48247AA3630AAA87" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_B182438834960BB631407AA3630B492F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5BBBF4BD85BE66DB48247AA3630AAA87" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_B182438834960BB631407AA3630B492F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_B182438834960BB631407AA3630B492F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5BBBF4BD85BE66DB48247AA3630AAA87" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_B182438834960BB631407AA3630B492F" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_SynchroniteLLCMember" xlink:label="loc_lpsn_SynchroniteLLCMember_D33786D0E7C849F4F4697AA3630BC97E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_B182438834960BB631407AA3630B492F" xlink:to="loc_lpsn_SynchroniteLLCMember_D33786D0E7C849F4F4697AA3630BC97E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_F0951E9E06E94E7A01307AA3630BC0E2" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_0DEFB7DC44F1230084AB7AA3630A6E15" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_F0951E9E06E94E7A01307AA3630BC0E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_5468703CC4A71F2CD2227AA3630BD53C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F0951E9E06E94E7A01307AA3630BC0E2" xlink:to="loc_us-gaap_SegmentDomain_5468703CC4A71F2CD2227AA3630BD53C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_5468703CC4A71F2CD2227AA3630BD53C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_F0951E9E06E94E7A01307AA3630BC0E2" xlink:to="loc_us-gaap_SegmentDomain_5468703CC4A71F2CD2227AA3630BD53C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_BusinessMember" xlink:label="loc_lpsn_BusinessMember_BE300877F7D3CBA5B6A67AA3630B1DA9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5468703CC4A71F2CD2227AA3630BD53C" xlink:to="loc_lpsn_BusinessMember_BE300877F7D3CBA5B6A67AA3630B1DA9" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ConsumerMember" xlink:label="loc_lpsn_ConsumerMember_6475CBA6A61776ABEA357AA3630B1C3C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_5468703CC4A71F2CD2227AA3630BD53C" xlink:to="loc_lpsn_ConsumerMember_6475CBA6A61776ABEA357AA3630B1C3C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_E2603B5E23F7C4F8CE2F7AA3630C1439" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_FDC07EC032A3F84763177AA3630BF9B3" xlink:to="loc_us-gaap_Goodwill_E2603B5E23F7C4F8CE2F7AA3630C1439" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_2F565A8737AC1F6E31897AA3630C3902" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_FDC07EC032A3F84763177AA3630BF9B3" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_2F565A8737AC1F6E31897AA3630C3902" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsFutureAmortizationExpenseDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/GoodwillAndIntangibleAssetsNarrativeDetails" 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/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_E38AB884E5FDD13164B37AA36301C99C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_3E1799B7D6626AC043D97AA362FF7D1B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_E38AB884E5FDD13164B37AA36301C99C" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_3E1799B7D6626AC043D97AA362FF7D1B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1B0DA93E6AA5DDF4A2277AA362FF9D3F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_3E1799B7D6626AC043D97AA362FF7D1B" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1B0DA93E6AA5DDF4A2277AA362FF9D3F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1B0DA93E6AA5DDF4A2277AA362FF9D3F" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1B0DA93E6AA5DDF4A2277AA362FF9D3F" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_TechnologyMember" xlink:label="loc_lpsn_TechnologyMember_1C838C6D4BFB123C3CB27AA362FFA978" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E" xlink:to="loc_lpsn_TechnologyMember_1C838C6D4BFB123C3CB27AA362FFA978" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CustomerContractsMember" xlink:label="loc_us-gaap_CustomerContractsMember_C8579CE6E9678296ADA57AA36300B6B0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E" xlink:to="loc_us-gaap_CustomerContractsMember_C8579CE6E9678296ADA57AA36300B6B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaap_TradeNamesMember_22A7A525B2C2B58400A07AA36300C7B6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E" xlink:to="loc_us-gaap_TradeNamesMember_22A7A525B2C2B58400A07AA36300C7B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_NoncompeteAgreementsMember" xlink:label="loc_us-gaap_NoncompeteAgreementsMember_EF68992C26913A812BB77AA36300FF64" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E" xlink:to="loc_us-gaap_NoncompeteAgreementsMember_EF68992C26913A812BB77AA36300FF64" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaap_PatentsMember_EE493ABF0679C58209DF7AA363019F90" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E" xlink:to="loc_us-gaap_PatentsMember_EE493ABF0679C58209DF7AA363019F90" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OtherIntangibleAssetsMember" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_F37062D60A3984841FFC7AA3630161F9" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_263DBF8E5EE8F961F2E17AA362FF961E" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_F37062D60A3984841FFC7AA3630161F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_FD9F7020DDE3B74123BC7AA36301A04F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_E38AB884E5FDD13164B37AA36301C99C" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_FD9F7020DDE3B74123BC7AA36301A04F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_7702155A153A43EF18E07AA36301236C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_E38AB884E5FDD13164B37AA36301C99C" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_7702155A153A43EF18E07AA36301236C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_0D047C04FD2AF5E9020C7AA36302A3B0" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_E38AB884E5FDD13164B37AA36301C99C" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_0D047C04FD2AF5E9020C7AA36302A3B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_3BAC181DFDBB7D7E4EE77AA36302F05B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_E38AB884E5FDD13164B37AA36301C99C" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_3BAC181DFDBB7D7E4EE77AA36302F05B" 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/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/NetLossPerShareNarrativeDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/NetLossPerShareReconciliationOfSharesUsedInCalculatingBasicAndDilutedEarningsPerShareDetails" 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/PropertyAndEquipmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_D7B83768926F8F67A1BF7AA362E96F41" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_65EEA3B118566240106F7AA362E84B14" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_D7B83768926F8F67A1BF7AA362E96F41" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_65EEA3B118566240106F7AA362E84B14" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3F381EF2865196082EB57AA362E9699F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_65EEA3B118566240106F7AA362E84B14" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3F381EF2865196082EB57AA362E9699F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_57A4982CCDDD0B599F737AA362E94059_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3F381EF2865196082EB57AA362E9699F" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_57A4982CCDDD0B599F737AA362E94059_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_57A4982CCDDD0B599F737AA362E94059" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_3F381EF2865196082EB57AA362E9699F" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_57A4982CCDDD0B599F737AA362E94059" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ComputerEquipmentAndSoftwareMember" xlink:label="loc_lpsn_ComputerEquipmentAndSoftwareMember_02C48F020D0ED13019397AA362E92022" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_57A4982CCDDD0B599F737AA362E94059" xlink:to="loc_lpsn_ComputerEquipmentAndSoftwareMember_02C48F020D0ED13019397AA362E92022" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_FurnitureEquipmentAndBuildingImprovementsMember" xlink:label="loc_lpsn_FurnitureEquipmentAndBuildingImprovementsMember_CF38652F2017F0F7C6527AA362E9A0D1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_57A4982CCDDD0B599F737AA362E94059" xlink:to="loc_lpsn_FurnitureEquipmentAndBuildingImprovementsMember_CF38652F2017F0F7C6527AA362E9A0D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_971340ED2697CBA180A67AA362E94E25" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_D7B83768926F8F67A1BF7AA362E96F41" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_971340ED2697CBA180A67AA362E94E25" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_5DD49AA09CD8A4794C077AA362E9FC07" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_D7B83768926F8F67A1BF7AA362E96F41" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_5DD49AA09CD8A4794C077AA362E9FC07" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_8D10F8E7BF61891816EF7AA362E9D796" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_D7B83768926F8F67A1BF7AA362E96F41" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_8D10F8E7BF61891816EF7AA362E9D796" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/PropertyAndEquipmentTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/Restructuring" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_CCFBB349A5306B47B3247AD345C06052" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_5F7F00D1FB56FA0E4F747AD345C00F16" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_CCFBB349A5306B47B3247AD345C06052" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_5F7F00D1FB56FA0E4F747AD345C00F16" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_F384D751ADD2908CDBE07AD345C09CD3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_5F7F00D1FB56FA0E4F747AD345C00F16" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_F384D751ADD2908CDBE07AD345C09CD3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_E211B2E53480E58F13837AD345C05E89_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_F384D751ADD2908CDBE07AD345C09CD3" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_E211B2E53480E58F13837AD345C05E89_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_E211B2E53480E58F13837AD345C05E89" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_F384D751ADD2908CDBE07AD345C09CD3" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_E211B2E53480E58F13837AD345C05E89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AccruedLiabilitiesMember" xlink:label="loc_us-gaap_AccruedLiabilitiesMember_280502879E3D135822CF7AD345C05C32" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_E211B2E53480E58F13837AD345C05E89" xlink:to="loc_us-gaap_AccruedLiabilitiesMember_280502879E3D135822CF7AD345C05C32" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_642666317508E3CF38D87AD345C168CB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_CCFBB349A5306B47B3247AD345C06052" xlink:to="loc_us-gaap_RestructuringCharges_642666317508E3CF38D87AD345C168CB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringReserve" xlink:label="loc_us-gaap_RestructuringReserve_EF41CB45EFF4541601A27AD345C1E235" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_CCFBB349A5306B47B3247AD345C06052" xlink:to="loc_us-gaap_RestructuringReserve_EF41CB45EFF4541601A27AD345C1E235" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringRestructuringExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCostAndReserveLineItems" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_6FB2066CC71FC43DFD867AD3417FA81B" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_A7A50648CC7C2729DAD07AD3417E8A09" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6FB2066CC71FC43DFD867AD3417FA81B" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_A7A50648CC7C2729DAD07AD3417E8A09" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_79D9F30B7CD454447F467AD3417FFFEC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_A7A50648CC7C2729DAD07AD3417E8A09" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_79D9F30B7CD454447F467AD3417FFFEC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_7D87038EDAD4526E7CF77AD3417FC0EE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_79D9F30B7CD454447F467AD3417FFFEC" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_7D87038EDAD4526E7CF77AD3417FC0EE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TypeOfRestructuringDomain" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_7D87038EDAD4526E7CF77AD3417FC0EE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_79D9F30B7CD454447F467AD3417FFFEC" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_7D87038EDAD4526E7CF77AD3417FC0EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EmployeeSeveranceMember" xlink:label="loc_us-gaap_EmployeeSeveranceMember_ED8997FAE75E804AB29D7AD3417F9B11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_7D87038EDAD4526E7CF77AD3417FC0EE" xlink:to="loc_us-gaap_EmployeeSeveranceMember_ED8997FAE75E804AB29D7AD3417F9B11" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_WindDownCostsMember" xlink:label="loc_lpsn_WindDownCostsMember_72B3156AEE6219C342B57AD3417F316D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_7D87038EDAD4526E7CF77AD3417FC0EE" xlink:to="loc_lpsn_WindDownCostsMember_72B3156AEE6219C342B57AD3417F316D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestructuringCharges" xlink:label="loc_us-gaap_RestructuringCharges_4C9CFD3ED2F21FB6C0807AD3417FE331" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_6FB2066CC71FC43DFD867AD3417FA81B" xlink:to="loc_us-gaap_RestructuringCharges_4C9CFD3ED2F21FB6C0807AD3417FE331" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringRestructuringLiabilityDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RestructuringTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RevenueRecognition" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.liveperson.com/role/RevenueRecognitionDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems" xlink:label="loc_us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems_4F3102E5EEC57D3A05B27AA3635CFF11" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable" xlink:label="loc_us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable_30F919749FE1631BEED77AA3635C3102" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems_4F3102E5EEC57D3A05B27AA3635CFF11" xlink:to="loc_us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable_30F919749FE1631BEED77AA3635C3102" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_3EC50B10C34DE2AA12947AA3635C2D43" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRecognitionMultipleDeliverableArrangementsTable_30F919749FE1631BEED77AA3635C3102" xlink:to="loc_us-gaap_RangeAxis_3EC50B10C34DE2AA12947AA3635C2D43" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_DCD84B8F98A963B68A0D7AA3635C2460_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_3EC50B10C34DE2AA12947AA3635C2D43" xlink:to="loc_us-gaap_RangeMember_DCD84B8F98A963B68A0D7AA3635C2460_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_DCD84B8F98A963B68A0D7AA3635C2460" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_3EC50B10C34DE2AA12947AA3635C2D43" xlink:to="loc_us-gaap_RangeMember_DCD84B8F98A963B68A0D7AA3635C2460" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_CB6024BBFC4E83F560217AA3635CFBB1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_DCD84B8F98A963B68A0D7AA3635C2460" xlink:to="loc_us-gaap_MinimumMember_CB6024BBFC4E83F560217AA3635CFBB1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_AF73F20692773BBB01F97AA3635C8E82" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_DCD84B8F98A963B68A0D7AA3635C2460" xlink:to="loc_us-gaap_MaximumMember_AF73F20692773BBB01F97AA3635C8E82" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_TerminationNoticePeriod2" xlink:label="loc_lpsn_TerminationNoticePeriod2_AD9A6654FE21B88458DF7AA3635C4A8D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRecognitionMultipleDeliverableArrangementsLineItems_4F3102E5EEC57D3A05B27AA3635CFF11" xlink:to="loc_lpsn_TerminationNoticePeriod2_AD9A6654FE21B88458DF7AA3635C4A8D" xlink:type="arc" />
  </link:definitionLink>
  <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/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_B45B61F237BB2CF24B707AA3631D2847" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_EC01870BF29D0044DA077AA3631B5B46" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_B45B61F237BB2CF24B707AA3631D2847" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_EC01870BF29D0044DA077AA3631B5B46" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_ADCEF1B765C97AC3D3577AA3631BB500" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_EC01870BF29D0044DA077AA3631B5B46" xlink:to="loc_us-gaap_StatementGeographicalAxis_ADCEF1B765C97AC3D3577AA3631BB500" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_ADCEF1B765C97AC3D3577AA3631BB500" xlink:to="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_ADCEF1B765C97AC3D3577AA3631BB500" xlink:to="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="loc_country_US_B4A3D434E8544274C7887AA3631C80F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75" xlink:to="loc_country_US_B4A3D434E8544274C7887AA3631C80F3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_IL" xlink:label="loc_country_IL_E6C9DE757CF2ECD6DD2F7AA3631C51B0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75" xlink:to="loc_country_IL_E6C9DE757CF2ECD6DD2F7AA3631C51B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_AU" xlink:label="loc_country_AU_2C701E7AF0AC266809DA7AA3631C8C8B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75" xlink:to="loc_country_AU_2C701E7AF0AC266809DA7AA3631C8C8B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_NL" xlink:label="loc_country_NL_FDE4FBA54FD5C03A68177AA3631C247F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75" xlink:to="loc_country_NL_FDE4FBA54FD5C03A68177AA3631C247F" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_UnitedKingdomGermanyJapanFranceItalyMember" xlink:label="loc_lpsn_UnitedKingdomGermanyJapanFranceItalyMember_B8574EF7FCF5E07A0E947AA3631CD6EE" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_4099AADD0413847A3C4E7AA3631CFD75" xlink:to="loc_lpsn_UnitedKingdomGermanyJapanFranceItalyMember_B8574EF7FCF5E07A0E947AA3631CD6EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AssetsNoncurrent" xlink:label="loc_us-gaap_AssetsNoncurrent_24155435CB4EC596650F7AA3631D5DAB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_B45B61F237BB2CF24B707AA3631D2847" xlink:to="loc_us-gaap_AssetsNoncurrent_24155435CB4EC596650F7AA3631D5DAB" 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/SegmentInformationRevenuesAttributableToDomesticAndForeignOperationsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_0717F1E42A8ACCEB8103806072852E1A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_D44C439543DD43A98ECB8060727FAF6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0717F1E42A8ACCEB8103806072852E1A" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_D44C439543DD43A98ECB8060727FAF6A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_70A1C10C815856433A478060727F5E40" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_D44C439543DD43A98ECB8060727FAF6A" xlink:to="loc_us-gaap_StatementGeographicalAxis_70A1C10C815856433A478060727F5E40" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_E07913D6C4FE70DF926C8060727F0BC9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementGeographicalAxis_70A1C10C815856433A478060727F5E40" xlink:to="loc_us-gaap_SegmentGeographicalDomain_E07913D6C4FE70DF926C8060727F0BC9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_E07913D6C4FE70DF926C8060727F0BC9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementGeographicalAxis_70A1C10C815856433A478060727F5E40" xlink:to="loc_us-gaap_SegmentGeographicalDomain_E07913D6C4FE70DF926C8060727F0BC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AmericasMember" xlink:label="loc_us-gaap_AmericasMember_AE5E56C388F95F8F71A48060727F58E9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_E07913D6C4FE70DF926C8060727F0BC9" xlink:to="loc_us-gaap_AmericasMember_AE5E56C388F95F8F71A48060727F58E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="loc_country_US_B08567FEB03339DFE9B78060727FC4FD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AmericasMember_AE5E56C388F95F8F71A48060727F58E9" xlink:to="loc_country_US_B08567FEB03339DFE9B78060727FC4FD" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_OtherAmericasMember" xlink:label="loc_lpsn_OtherAmericasMember_E29C0511A3E2C4A1AFDE8060727F150F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AmericasMember_AE5E56C388F95F8F71A48060727F58E9" xlink:to="loc_lpsn_OtherAmericasMember_E29C0511A3E2C4A1AFDE8060727F150F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EMEAMember" xlink:label="loc_us-gaap_EMEAMember_9DFD57110FB57BE4841B80607285A9F6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_E07913D6C4FE70DF926C8060727F0BC9" xlink:to="loc_us-gaap_EMEAMember_9DFD57110FB57BE4841B80607285A9F6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_GB" xlink:label="loc_country_GB_F183EA6171A881AEED36806072850D19" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EMEAMember_9DFD57110FB57BE4841B80607285A9F6" xlink:to="loc_country_GB_F183EA6171A881AEED36806072850D19" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/exch/2017/exch-2017-01-31.xsd#exch_XPST" xlink:label="loc_exch_XPST_F77EE7778505E27919F8806072851BCD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentGeographicalDomain_E07913D6C4FE70DF926C8060727F0BC9" xlink:to="loc_exch_XPST_F77EE7778505E27919F8806072851BCD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_9471F77D586F66F8608A806072854D2E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_0717F1E42A8ACCEB8103806072852E1A" xlink:to="loc_us-gaap_Revenues_9471F77D586F66F8608A806072854D2E" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/SegmentInformationSummaryOfFinancialInformationBySegmentDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_D80AF34924CE63CECF6580B3D81A492E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_BE928D7AB445355889E880B3D81A7D23" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_D80AF34924CE63CECF6580B3D81A492E" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_BE928D7AB445355889E880B3D81A7D23" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_C51F0C766CA9528DC39A80B3D81AB4B8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_BE928D7AB445355889E880B3D81A7D23" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_C51F0C766CA9528DC39A80B3D81AB4B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_C2D497B3B3788D5717DF80B3D81AEC7C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_C51F0C766CA9528DC39A80B3D81AB4B8" xlink:to="loc_us-gaap_SegmentDomain_C2D497B3B3788D5717DF80B3D81AEC7C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_C2D497B3B3788D5717DF80B3D81AEC7C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_C51F0C766CA9528DC39A80B3D81AB4B8" xlink:to="loc_us-gaap_SegmentDomain_C2D497B3B3788D5717DF80B3D81AEC7C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_BusinessMember" xlink:label="loc_lpsn_BusinessMember_CA4FB318C6C3FD94602C80B3D81A5BD2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_C2D497B3B3788D5717DF80B3D81AEC7C" xlink:to="loc_lpsn_BusinessMember_CA4FB318C6C3FD94602C80B3D81A5BD2" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ConsumerMember" xlink:label="loc_lpsn_ConsumerMember_55A43BAF44A970860F8780B3D81AA256" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_C2D497B3B3788D5717DF80B3D81AEC7C" xlink:to="loc_lpsn_ConsumerMember_55A43BAF44A970860F8780B3D81AA256" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_392A12BDDEC8572C779D80B3D81AA8CF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_BE928D7AB445355889E880B3D81A7D23" xlink:to="loc_us-gaap_ConsolidationItemsAxis_392A12BDDEC8572C779D80B3D81AA8CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_719070FF59F5FE563FD180B3D81A8388_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConsolidationItemsAxis_392A12BDDEC8572C779D80B3D81AA8CF" xlink:to="loc_us-gaap_ConsolidationItemsDomain_719070FF59F5FE563FD180B3D81A8388_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_719070FF59F5FE563FD180B3D81A8388" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConsolidationItemsAxis_392A12BDDEC8572C779D80B3D81AA8CF" xlink:to="loc_us-gaap_ConsolidationItemsDomain_719070FF59F5FE563FD180B3D81A8388" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_E1979CA67EC13860ED1680B3D81AD10E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_719070FF59F5FE563FD180B3D81A8388" xlink:to="loc_us-gaap_OperatingSegmentsMember_E1979CA67EC13860ED1680B3D81AD10E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_B9C5FF43EB4AB1B3A97D80B3D81A65EB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConsolidationItemsDomain_719070FF59F5FE563FD180B3D81A8388" xlink:to="loc_us-gaap_CorporateNonSegmentMember_B9C5FF43EB4AB1B3A97D80B3D81A65EB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SegmentReportingInformationRevenueAbstract" xlink:label="loc_us-gaap_SegmentReportingInformationRevenueAbstract_909D28BBA32F17E4CFB080B3D81AA38C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_D80AF34924CE63CECF6580B3D81A492E" xlink:to="loc_us-gaap_SegmentReportingInformationRevenueAbstract_909D28BBA32F17E4CFB080B3D81AA38C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_BusinessServicesRevenue" xlink:label="loc_lpsn_BusinessServicesRevenue_FD08BD6097160D82E2B980B3D81AB21C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_909D28BBA32F17E4CFB080B3D81AA38C" xlink:to="loc_lpsn_BusinessServicesRevenue_FD08BD6097160D82E2B980B3D81AB21C" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ConsumerServicesRevenue" xlink:label="loc_lpsn_ConsumerServicesRevenue_2077B9BB8E2E4A01365B80B3D81A0A08" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_909D28BBA32F17E4CFB080B3D81AA38C" xlink:to="loc_lpsn_ConsumerServicesRevenue_2077B9BB8E2E4A01365B80B3D81A0A08" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ProfessionalServicesRevenue" xlink:label="loc_lpsn_ProfessionalServicesRevenue_BEC555CE357ECCAEFCC080B3D81A28A7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_909D28BBA32F17E4CFB080B3D81AA38C" xlink:to="loc_lpsn_ProfessionalServicesRevenue_BEC555CE357ECCAEFCC080B3D81A28A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_843174518B4071FD9AEF80B3D81A1227" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationRevenueAbstract_909D28BBA32F17E4CFB080B3D81AA38C" xlink:to="loc_us-gaap_Revenues_843174518B4071FD9AEF80B3D81A1227" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_CostOfRevenue" xlink:label="loc_us-gaap_CostOfRevenue_452B3FB74A34B123B9CE80B3D81AA8F4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_D80AF34924CE63CECF6580B3D81A492E" xlink:to="loc_us-gaap_CostOfRevenue_452B3FB74A34B123B9CE80B3D81AA8F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaap_SellingAndMarketingExpense_046C0C6899467DCD2AC380B3D81AFE45" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_D80AF34924CE63CECF6580B3D81A492E" xlink:to="loc_us-gaap_SellingAndMarketingExpense_046C0C6899467DCD2AC380B3D81AFE45" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_3A204C93ECDB3C9F5FA280B3D81A8C66" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_D80AF34924CE63CECF6580B3D81A492E" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_3A204C93ECDB3C9F5FA280B3D81A8C66" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_SegmentReportingUnallocatedCorporateExpenses" xlink:label="loc_lpsn_SegmentReportingUnallocatedCorporateExpenses_756897A420ED39AB83FE80B3D81AE835" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_D80AF34924CE63CECF6580B3D81A492E" xlink:to="loc_lpsn_SegmentReportingUnallocatedCorporateExpenses_756897A420ED39AB83FE80B3D81AE835" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_D215CC37FD623C8381D980B3D81A00D3" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_D80AF34924CE63CECF6580B3D81A492E" xlink:to="loc_us-gaap_OperatingIncomeLoss_D215CC37FD623C8381D980B3D81A00D3" 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/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4D4C79BD39246B53D395805F2D443405" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4D4C79BD39246B53D395805F2D443405" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_9C0958335A21506EBF63805F2D444CC5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4D4C79BD39246B53D395805F2D443405" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_9C0958335A21506EBF63805F2D444CC5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_0CFC0C2C9B449E45CFEA805F2D4402C0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_9C0958335A21506EBF63805F2D444CC5" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_0CFC0C2C9B449E45CFEA805F2D4402C0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_0CFC0C2C9B449E45CFEA805F2D4402C0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_9C0958335A21506EBF63805F2D444CC5" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_0CFC0C2C9B449E45CFEA805F2D4402C0" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_A2012StockRepurchaseProgramMember" xlink:label="loc_lpsn_A2012StockRepurchaseProgramMember_D49F93BC330572AB4F0C805F2D44ED1B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_0CFC0C2C9B449E45CFEA805F2D4402C0" xlink:to="loc_lpsn_A2012StockRepurchaseProgramMember_D49F93BC330572AB4F0C805F2D44ED1B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_PeriodReportedAxis" xlink:label="loc_lpsn_PeriodReportedAxis_1902248E9F646CDD8030805F2D457659" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4D4C79BD39246B53D395805F2D443405" xlink:to="loc_lpsn_PeriodReportedAxis_1902248E9F646CDD8030805F2D457659" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_PeriodReportedDomain" xlink:label="loc_lpsn_PeriodReportedDomain_492CD90CEA0AB93BECFE805F2D453C92_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_lpsn_PeriodReportedAxis_1902248E9F646CDD8030805F2D457659" xlink:to="loc_lpsn_PeriodReportedDomain_492CD90CEA0AB93BECFE805F2D453C92_default" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_PeriodReportedDomain" xlink:label="loc_lpsn_PeriodReportedDomain_492CD90CEA0AB93BECFE805F2D453C92" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_lpsn_PeriodReportedAxis_1902248E9F646CDD8030805F2D457659" xlink:to="loc_lpsn_PeriodReportedDomain_492CD90CEA0AB93BECFE805F2D453C92" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_AmendedMember" xlink:label="loc_lpsn_AmendedMember_75647D93D9226336230B805F2D45E8FD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_PeriodReportedDomain_492CD90CEA0AB93BECFE805F2D453C92" xlink:to="loc_lpsn_AmendedMember_75647D93D9226336230B805F2D45E8FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_D5C59B25ABC7896630D3805F2D45101E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4D4C79BD39246B53D395805F2D443405" xlink:to="loc_us-gaap_PlanNameAxis_D5C59B25ABC7896630D3805F2D45101E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_D5C59B25ABC7896630D3805F2D45101E" xlink:to="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_D5C59B25ABC7896630D3805F2D45101E" xlink:to="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_NineteenNinetyEightPlanMember" xlink:label="loc_lpsn_NineteenNinetyEightPlanMember_178D0D609EF52DA017AE805F2D45526B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86" xlink:to="loc_lpsn_NineteenNinetyEightPlanMember_178D0D609EF52DA017AE805F2D45526B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_TwoThousandPlanMember" xlink:label="loc_lpsn_TwoThousandPlanMember_FB2E04D66FE2DE708774805F2D45BCBA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86" xlink:to="loc_lpsn_TwoThousandPlanMember_FB2E04D66FE2DE708774805F2D45BCBA" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_NineteenNinetyEightAndTwoThousandPlanMember" xlink:label="loc_lpsn_NineteenNinetyEightAndTwoThousandPlanMember_9EE3460D26353F417E24805F2D4575BF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86" xlink:to="loc_lpsn_NineteenNinetyEightAndTwoThousandPlanMember_9EE3460D26353F417E24805F2D4575BF" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_TwoThousandNinePlanMember" xlink:label="loc_lpsn_TwoThousandNinePlanMember_393BE9A1FC023B8ED442805F2D45427E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86" xlink:to="loc_lpsn_TwoThousandNinePlanMember_393BE9A1FC023B8ED442805F2D45427E" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_EmployeeStockPurchasePlanTwentyTenMember" xlink:label="loc_lpsn_EmployeeStockPurchasePlanTwentyTenMember_A2EBB1BAFC5A1CCE2C8E805F2D458B5F" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_26B41B381533F93992F8805F2D458C86" xlink:to="loc_lpsn_EmployeeStockPurchasePlanTwentyTenMember_A2EBB1BAFC5A1CCE2C8E805F2D458B5F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_F2A13236DC8FE341DB5F805F2D46C5AF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4D4C79BD39246B53D395805F2D443405" xlink:to="loc_us-gaap_AwardTypeAxis_F2A13236DC8FE341DB5F805F2D46C5AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0BCFD1407F8CEFC595A7805F2D46CA88_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_F2A13236DC8FE341DB5F805F2D46C5AF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0BCFD1407F8CEFC595A7805F2D46CA88_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0BCFD1407F8CEFC595A7805F2D46CA88" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_F2A13236DC8FE341DB5F805F2D46C5AF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0BCFD1407F8CEFC595A7805F2D46CA88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_1F356B8A851C1CB46EB48061B3097BAC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0BCFD1407F8CEFC595A7805F2D46CA88" xlink:to="loc_us-gaap_EmployeeStockOptionMember_1F356B8A851C1CB46EB48061B3097BAC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_E16407F20783BE70C417805F2D46E069" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0BCFD1407F8CEFC595A7805F2D46CA88" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_E16407F20783BE70C417805F2D46E069" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_DA3F4500D98B08B8233A805F2D4647FD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_DA3F4500D98B08B8233A805F2D4647FD" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_StockRepurchaseProgramIncreaseToAuthorizedAmount" xlink:label="loc_lpsn_StockRepurchaseProgramIncreaseToAuthorizedAmount_89624975289E0C03DDCA805F2D4698CF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_lpsn_StockRepurchaseProgramIncreaseToAuthorizedAmount_89624975289E0C03DDCA805F2D4698CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_10764AA655419EB1D247805F2D46EEFA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_TreasuryStockShares_10764AA655419EB1D247805F2D46EEFA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_E8FBF9DDAA3D777A64C4805F2D46B4CA" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_E8FBF9DDAA3D777A64C4805F2D46B4CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_9F350CD20DDBE83DE77A805F2D464E57" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_9F350CD20DDBE83DE77A805F2D464E57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_304966C2DE7538ECEC47805F2D476BC8" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_304966C2DE7538ECEC47805F2D476BC8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_E84D2FF2A695D34BE3AE805F2D472A61" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_E84D2FF2A695D34BE3AE805F2D472A61" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPeriodUsedToDetermineVolatility" xlink:label="loc_lpsn_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPeriodUsedToDetermineVolatility_C988AAC0C08BA0BF8F87805F2D47D8BB" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_lpsn_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsPeriodUsedToDetermineVolatility_C988AAC0C08BA0BF8F87805F2D47D8BB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_8C593473A2A640114BF1805F2D47345D" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_8C593473A2A640114BF1805F2D47345D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_B0BF945C5F812A2B9ED8805F2D477A58" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_B0BF945C5F812A2B9ED8805F2D477A58" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationTerm" xlink:label="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationTerm_00835931D835386B123F805F2D473059" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationTerm_00835931D835386B123F805F2D473059" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_17614BCEC447F7334779805F2D47BDF6" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_17614BCEC447F7334779805F2D47BDF6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_37304B768CFB9F8311C6805F2D47D5B6" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_37304B768CFB9F8311C6805F2D47D5B6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_347CBB182C38426B26CD805F2D479F5D" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_347CBB182C38426B26CD805F2D479F5D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_53CA3E9594FDB953BFFB805F2D476738" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_8ED06DC6F6579878FBE0805F2D462254" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_53CA3E9594FDB953BFFB805F2D476738" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquitySummaryOfOptionsByRangeOfExercisePricesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_723ECD42A1D616F09A827AA362374586" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_723ECD42A1D616F09A827AA362374586" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_948648EFF2D42A9642E57AA362372B88" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable_723ECD42A1D616F09A827AA362374586" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_948648EFF2D42A9642E57AA362372B88" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_948648EFF2D42A9642E57AA362372B88" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_948648EFF2D42A9642E57AA362372B88" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeOneMember" xlink:label="loc_lpsn_ExercisePriceRangeOneMember_07353566F459AE5745097AA36238BCE7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeOneMember_07353566F459AE5745097AA36238BCE7" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeTwoMember" xlink:label="loc_lpsn_ExercisePriceRangeTwoMember_2DF1BBEF564F3C2E4AE87AA36238BACF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeTwoMember_2DF1BBEF564F3C2E4AE87AA36238BACF" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeThreeMember" xlink:label="loc_lpsn_ExercisePriceRangeThreeMember_681EDDB30E48AC4B94237AA36239ED43" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeThreeMember_681EDDB30E48AC4B94237AA36239ED43" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeFourMember" xlink:label="loc_lpsn_ExercisePriceRangeFourMember_F20F801DB9C0DDF07CCD7AA36239ABF5" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeFourMember_F20F801DB9C0DDF07CCD7AA36239ABF5" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeFiveMember" xlink:label="loc_lpsn_ExercisePriceRangeFiveMember_6BA3041192F030BCCD037AA3623913DD" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeFiveMember_6BA3041192F030BCCD037AA3623913DD" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeSixMember" xlink:label="loc_lpsn_ExercisePriceRangeSixMember_7900EB8574858167DAEA7AA3623925C6" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeSixMember_7900EB8574858167DAEA7AA3623925C6" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeSevenMember" xlink:label="loc_lpsn_ExercisePriceRangeSevenMember_F98DE2B9815C731AF24F7AA362394510" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeSevenMember_F98DE2B9815C731AF24F7AA362394510" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeEightMember" xlink:label="loc_lpsn_ExercisePriceRangeEightMember_7E5E0AB95FC52CC3FB1B7AA3623ACD31" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeEightMember_7E5E0AB95FC52CC3FB1B7AA3623ACD31" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeNineMember" xlink:label="loc_lpsn_ExercisePriceRangeNineMember_E873B6D13A12692469447AA3623A771B" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeNineMember_E873B6D13A12692469447AA3623A771B" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ExercisePriceRangeTenMember" xlink:label="loc_lpsn_ExercisePriceRangeTenMember_037D42825988744AD7187AA3623AB3EA" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_81D2F76FFAC04CD0B2B07AA362370744" xlink:to="loc_lpsn_ExercisePriceRangeTenMember_037D42825988744AD7187AA3623AB3EA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_310C6FDC4627166AD6B07AA3623BEDA4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_310C6FDC4627166AD6B07AA3623BEDA4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_F3A1E66469B795DF63D77AA3623B6038" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_F3A1E66469B795DF63D77AA3623B6038" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_9959C564DCE901ACECBD7AA3623B6D09" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_9959C564DCE901ACECBD7AA3623B6D09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_265CF72107CA55B764D17AA3623BBF70" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_265CF72107CA55B764D17AA3623BBF70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_91B99ADB608D8E9671AD7AA3623CA1C7" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_91B99ADB608D8E9671AD7AA3623CA1C7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_5B289CD16E571A95F7DA7AA3623C4576" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_5B289CD16E571A95F7DA7AA3623C4576" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_D68104AEBD10B5A4EFD17AA3623C50D2" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_FBF758608387811DF01F7AA3623A9573" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_D68104AEBD10B5A4EFD17AA3623C50D2" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.liveperson.com/role/StockholdersEquitySummaryOfRestrictedStockUnitActivityAndWeightedAverageExercisePriceDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_911F528E0557F6E9763D7AA362211E86" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9F2E79845E88D8B56A6D7AA36220B70E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_911F528E0557F6E9763D7AA362211E86" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9F2E79845E88D8B56A6D7AA36220B70E" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_127886327011EC1F5C997AA36220FB99" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9F2E79845E88D8B56A6D7AA36220B70E" xlink:to="loc_us-gaap_AwardTypeAxis_127886327011EC1F5C997AA36220FB99" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B6A9FBDB5160ED2FE3567AA362208812_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_127886327011EC1F5C997AA36220FB99" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B6A9FBDB5160ED2FE3567AA362208812_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B6A9FBDB5160ED2FE3567AA362208812" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_127886327011EC1F5C997AA36220FB99" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B6A9FBDB5160ED2FE3567AA362208812" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_16962466483159808D9B7AA36220DE36" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_B6A9FBDB5160ED2FE3567AA362208812" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_16962466483159808D9B7AA36220DE36" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_40D46FD849E0D39253287AA36221962E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_911F528E0557F6E9763D7AA362211E86" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_40D46FD849E0D39253287AA36221962E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_C2367FC1993685771CF57AA36221907D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_40D46FD849E0D39253287AA36221962E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_C2367FC1993685771CF57AA36221907D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_69C5E0075580FAD2EA517AA36221B117" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_40D46FD849E0D39253287AA36221962E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_69C5E0075580FAD2EA517AA36221B117" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_F238E1310A46A8F568337AA3622266FD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_40D46FD849E0D39253287AA36221962E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_F238E1310A46A8F568337AA3622266FD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_36DBA24B7FFDF6E41C817AA362227E47" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_40D46FD849E0D39253287AA36221962E" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsForfeitures_36DBA24B7FFDF6E41C817AA362227E47" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpectedToVest" xlink:label="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpectedToVest_0D5C3076FED49BF2944B7AA36222AA53" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_911F528E0557F6E9763D7AA362211E86" xlink:to="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpectedToVest_0D5C3076FED49BF2944B7AA36222AA53" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageGrantDateFairValueAbstractRollForward" xlink:label="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageGrantDateFairValueAbstractRollForward_D8D6CCAD755A7F88AB9F7AA3622266DA" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_911F528E0557F6E9763D7AA362211E86" xlink:to="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageGrantDateFairValueAbstractRollForward_D8D6CCAD755A7F88AB9F7AA3622266DA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1632FB588DEFFD41AD427AA36222ACD0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageGrantDateFairValueAbstractRollForward_D8D6CCAD755A7F88AB9F7AA3622266DA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1632FB588DEFFD41AD427AA36222ACD0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_9C97AB4DCD7A329D5F627AA362234A0F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageGrantDateFairValueAbstractRollForward_D8D6CCAD755A7F88AB9F7AA3622266DA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_9C97AB4DCD7A329D5F627AA362234A0F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_F2961BE622392F6B80367AA36223AF8E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageGrantDateFairValueAbstractRollForward_D8D6CCAD755A7F88AB9F7AA3622266DA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_F2961BE622392F6B80367AA36223AF8E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_B41FBEB8F5B7F1B49D827AA362235408" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsWeightedAverageGrantDateFairValueAbstractRollForward_D8D6CCAD755A7F88AB9F7AA3622266DA" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_B41FBEB8F5B7F1B49D827AA362235408" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpectedToVestWeightedAverageGrantDateFairValue" xlink:label="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpectedToVestWeightedAverageGrantDateFairValue_9DE90C310623FBAB11B47AA3622467E7" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_911F528E0557F6E9763D7AA362211E86" xlink:to="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpectedToVestWeightedAverageGrantDateFairValue_9DE90C310623FBAB11B47AA3622467E7" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueRollForward" xlink:label="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueRollForward_82E2C7B255C22CEA661E7AA36224F6FB" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_911F528E0557F6E9763D7AA362211E86" xlink:to="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueRollForward_82E2C7B255C22CEA661E7AA36224F6FB" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueNonvestedAndOutstanding" xlink:label="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueNonvestedAndOutstanding_224CB2CE2EE85D667CEE7AA36224C4B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueRollForward_82E2C7B255C22CEA661E7AA36224F6FB" xlink:to="loc_lpsn_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueNonvestedAndOutstanding_224CB2CE2EE85D667CEE7AA36224C4B4" xlink:type="arc" />
    <link:loc xlink:href="lpsn-20170630.xsd#lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueExpectedToVest" xlink:label="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueExpectedToVest_9C9CE3EC6F652EAA7C457AA36224856D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueRollForward_82E2C7B255C22CEA661E7AA36224F6FB" xlink:to="loc_lpsn_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsAggregateIntrinsicValueExpectedToVest_9C9CE3EC6F652EAA7C457AA36224856D" 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:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E26E5217F660ADFC26DB805D96185FD8" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_39ECFCBAAA5771FE597C805D96177E6A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E26E5217F660ADFC26DB805D96185FD8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_39ECFCBAAA5771FE597C805D96177E6A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeAxis" xlink:label="loc_us-gaap_RangeAxis_4D5EAD8971E9105DC3AC805DEB3C3D4E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_39ECFCBAAA5771FE597C805D96177E6A" xlink:to="loc_us-gaap_RangeAxis_4D5EAD8971E9105DC3AC805DEB3C3D4E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_66606EC23F6D23A9EF48805DEBE9E8CF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RangeAxis_4D5EAD8971E9105DC3AC805DEB3C3D4E" xlink:to="loc_us-gaap_RangeMember_66606EC23F6D23A9EF48805DEBE9E8CF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_RangeMember" xlink:label="loc_us-gaap_RangeMember_66606EC23F6D23A9EF48805DEBE9E8CF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RangeAxis_4D5EAD8971E9105DC3AC805DEB3C3D4E" xlink:to="loc_us-gaap_RangeMember_66606EC23F6D23A9EF48805DEBE9E8CF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MaximumMember" xlink:label="loc_us-gaap_MaximumMember_594C8CAA07150A28ADFF805E25BE697B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_66606EC23F6D23A9EF48805DEBE9E8CF" xlink:to="loc_us-gaap_MaximumMember_594C8CAA07150A28ADFF805E25BE697B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_A5872B7FF06C1CBEF72B805E5317E1D7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RangeMember_66606EC23F6D23A9EF48805DEBE9E8CF" xlink:to="loc_us-gaap_MinimumMember_A5872B7FF06C1CBEF72B805E5317E1D7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_ED5A196D43588765D85D8059529FF647" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E26E5217F660ADFC26DB805D96185FD8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_ED5A196D43588765D85D8059529FF647" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_3D36CE5A59C606C47E11805952A1CB8D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E26E5217F660ADFC26DB805D96185FD8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_3D36CE5A59C606C47E11805952A1CB8D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_A2D8F84898349A3D3AE9805952A6097F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E26E5217F660ADFC26DB805D96185FD8" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_A2D8F84898349A3D3AE9805952A6097F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_7CD039B15A0C635D6655805952A6BE56" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_E26E5217F660ADFC26DB805D96185FD8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_7CD039B15A0C635D6655805952A6BE56" xlink:type="arc" />
  </link:definitionLink>
</link:linkbase>
