excellence (n.)youdaoicibaDictYouDict[excellence 词源字典]
mid-14c., from Old French excellence, from Latin excellentia "superiority, excellence," from excellentem (nominative excellens) "towering, distinguished, superior" (see excellent).[excellence etymology, excellence origin, 英语词源]
excellency (n.)youdaoicibaDictYouDict
"high rank," c. 1200, from Latin excellentia "superiority, excellence," from excellentem (see excellent); as a title of honor it dates from early 14c.
par excellenceyoudaoicibaDictYouDict
French, from Latin per excellentiam "by the way of excellence." From French par "by way of, by means of," from Latin per (see per). For second element see excellence.