affirmation (n.)

early 15c., "assertion that something is true," from Old French afermacion "confirmation" (14c.), from Latin affirmationem (nominative affirmatio) "an affirmation, solid assurance," noun of action from past-participle stem of affirmare "to make steady; strengthen; confirm," from ad "to" (see ad-) + firmare "strengthen, make firm," from firmus "strong" (see firm (adj.)). In law, as the word for the conscientious objector alternative to oath-taking (Quakers, Moravians, etc.), it is attested from 1690s; if false, it incurs the same penalty as perjury.