[Jan.sen.ism] n [F jansenisme, fr. Cornelis Jansen] (ca. 1656) 1: a system of doctrine based on moral determinism, defended by various reformist factions among 17th and 18th century western European Roman Catholic clergy, religious, and scholars, and condemned as heretical by papal authority
2: a puritanical attitude (as toward sex) -- Jan.sen.ist n -- Jan.sen.is.tic adj