vivacity (n.)youdaoicibaDictYouDict[vivacity 词源字典]
early 15c., "liveliness, vigor," from Old French vivacite or directly from Latin vivacitatem (nominative vivacitas) "vital force, liveliness," from vivax (genitive vivacis) "lively," also "long-lived," from vivere "to live" (see vital).[vivacity etymology, vivacity origin, 英语词源]