affirmare = “to present (something) as fixed, firm, or true; assert, maintain, confirm or corroborate”. Itself from Latin roots ad (“to, towards, at”) + firmō (“strengthen, fortify”).

An appeal to conscience as a form of positive assertion without specific religious reference or pledge to sacred or venerated objects or deities. Also, a solemn and formal asseveration in substitution for an oath that an affidavit is true and that the witness will tell the truth.