perpetuity (n.)youdaoicibaDictYouDict[perpetuity 词源字典]
late 14c., from Old French perpetuité "permanence, duration" (13c., Modern French perpétuité) and directly from Latin perpetuitatem (nominative perpetuitas) "uninterrupted duration, continuity, continuous succession," from perpetuus (see perpetual).[perpetuity etymology, perpetuity origin, 英语词源]