What is the Latin word for affirmative?

The usual Latin words for “affirmative” are aiō, affirmō, affirmātīvus; also affirmātiō. The right choice depends on the sense; see the distinctions below.

English → Latin

“affirmative” in Latin

aiōto say, speak, assert, say “yes”, affirm (also in reply); to say, argue affirmōto present (something) as fixed, firm, or true; affirm, assert, maintain; to strengthen, confirm, corroborate; to make c affirmātīvusaffirming, affirmative affirmātiōaffirmation, declaration, assertion; confirmation

The English word affirmative itself goes back to Latin firmō, through affirmativus.

Riddle & Arnold A Copious and Critical English–Latin Lexicon, 1864

affirmative

aiens (opposed to negans, “negantia contraria aientibus,” Cic.): affirmans (asserting that something is so: in late grammarians, affirmativus). An affirmative answer, affirmatio.

Quick answer

What is the Latin word for affirmative?: The usual Latin words for “affirmative” are aiō, affirmō, affirmātīvus; also affirmātiō. The right choice depends on the sense; see the distinctions below.

Entry from J. E. Riddle & T. K. Arnold, A Copious and Critical English–Latin Lexicon (rev. C. Anthon, New York: Harper, 1864), digitised by Fergus J. P. Walsh, CC BY-SA 4.0; Latin markup adapted by latindictionary.co.