The Collaborative International Dictionary of English v.0.48:
Affirmer \Af*firm"er\, n. One who affirms. [1913 Webster]WordNet (r) 3.0 (2006):
affirmer n 1: someone who claims to speak the truth; "a bold asserter"; "a declarer of his intentions"; "affirmers of traditional doctrine"; "an asseverator of strong convictions"; "an avower of his own great intelligence" [syn: asserter, declarer, affirmer, asseverator, avower]