asseverate (v.)youdaoicibaDictYouDict[asseverate 词源字典]
1791, from Latin asseveratus, past participle of asseverare "to affirm, insist on, maintain," from ad- "to" (see ad-) + severus "serious, severe" (see severe). Related: Asseverated; asseverating.[asseverate etymology, asseverate origin, 英语词源]