H. P. Grice, "The implicatures of the Square of Opposition -- as dismissed by P. F. Strawson"

 af-firmo (better adf- ), āvi, ātum, 1, v. a. I. To present a thing in words, as fixed, firm, i. e. certain, true; to assert, maintain, aver, declare, asseverate, affirm: “dicendum est mihi, sed ita, nihil ut adfirmem, quaeram omnia,” Cic. Div. 2, 3; so id. Att. 13, 23; id. Brut. 1, 1: “jure jurando,” Liv. 29, 23: “quidam plures Deo ortos adfirmant,” Tac. G. 2; cf. id. Agr. 10: “adfirmavit non daturum se,” he protested that he would give nothing, Suet. Aug. 42.—Impers.: “atque affirmatur,” Tac. H. 2, 49.—Hence, II. To give confirmation of the truth of a thing, to strengthen, to confirm, corroborate, sanction: “adfirmare spem alicui,” Liv. 1, 1: “opinionem,” id. 32, 35: “dicta alicujus,” id. 28, 2: “aliquid auctoritate sua,” id. 26, 24: “populi Romani virtutem armis,” Tac. H. 4, 73: “secuta anceps valetudo iram Deūm adfirmavit,” id. A. 14, 22.—Hence, * affirmanter (adf- ), adv. (of the absol. P. a. affirmans), with assurance or certainty, assuredly: “praedicere aliquid,” Gell. 14, 1, 24; and: af-firmātē (adf- ), adv. (of the absol. P. a. affirmatus), with asseveration, with assurance, certainly, assuredly, positively: “quod adfirmate, quasi Deo teste promiserit, id tenendum est,” Cic. Off. 3, 29.—Sup.: “adfirmatissime scribere aliquid,” Gell. 10, 12, 9.