Entry 1 sense Webster, 1913 Jansenism /jăn'-sĭn-ĭzˌ-əm/ · Jan·sen·ism · IPA /dʒˈænsɪnˌɪzəm/ 01 n. The doctrine of Jansen regarding free will and divine grace. 1. The doctrine of Jansen regarding free will and divine grace.(Eccl. Hist.)