as·sev·er·ate \əˈsevəˌrāt, aˈ-, usu -ād.+V\transitive verb (-ed/-ing/-s) Etymology: Latin asseveratus, adseveratus, past participle of asseverare, adseverare, from ad- + -severare (from severus serious, severe) — more at severe : to affirm or aver positively or earnestly < admit or asseverate the necessity and inevitability of almost everything that follows — S.C.Pepper > Synonyms:see swear