aver (v.)youdaoicibaDictYouDict[aver 词源字典]
late 14c., from Old French averer "verify," from Vulgar Latin *adverare "make true, prove to be true," from Latin ad- "to" (see ad-) + verus "true" (see very). Related: Averred; averring.[aver etymology, aver origin, 英语词源]