sincerity (n.)youdaoicibaDictYouDict[sincerity 词源字典]
early 15c., "honesty, genuineness," from Middle French sinceritie (early 16c., Modern French sincérité) and directly from Latin sinceritatem (nominative sinceritas) "purity, soundness, wholeness," from sincerus "whole, clean, uninjured," figuratively "sound, genuine, pure, true, candid, truthful" (see sincere).[sincerity etymology, sincerity origin, 英语词源]