The Collaborative International Dictionary of English v.0.48:

Affirm \Af*firm"\ ([a^]f*f[~e]rm"), v. t. [imp. & p. p.
   Affirmed (-f[~e]rmd"); p. pr. & vb. n. Affirming.] [OE.
   affermen, OF. afermer, F. affirmer, affermir, fr. L.
   affirmare; ad + firmare to make firm, firmus firm. See
   Firm.]
   1. To make firm; to confirm, or ratify; esp. (Law), to assert
      or confirm, as a judgment, decree, or order, brought
      before an appellate court for review.
      [1913 Webster]

   2. To assert positively; to tell with confidence; to aver; to
      maintain as true; -- opposed to deny.
      [1913 Webster]

            Jesus, . . . whom Paul affirmed to be alive. --Acts
                                                  xxv. 19.
      [1913 Webster]

   3. (Law) To declare, as a fact, solemnly, under judicial
      sanction. See Affirmation, 4.
      [1913 Webster]

   Syn: To assert; aver; declare; asseverate; assure; pronounce;
        protest; avouch; confirm; establish; ratify.

   Usage: To Affirm, Asseverate, Aver, Protest. We
          affirm when we declare a thing as a fact or a
          proposition. We asseverate it in a peculiarly earnest
          manner, or with increased positiveness as what can not
          be disputed. We aver it, or formally declare it to be
          true, when we have positive knowledge of it. We
          protest in a more public manner and with the energy of
          perfect sincerity. People asseverate in order to
          produce a conviction of their veracity; they aver when
          they are peculiarly desirous to be believed; they
          protest when they wish to free themselves from
          imputations, or to produce a conviction of their
          innocence.
          [1913 Webster]

WordNet (r) 3.0 (2006):

Affirmed
    n 1: thoroughbred that won the triple crown in 1978

Moby Thesaurus II by Grady Ward, 1.0:

68 Moby Thesaurus words for "affirmed":
   accepted, accessible, acknowledged, admitted, alleged, allowed,
   announced, approved, asserted, asseverated, attested,
   authenticated, averred, avouched, avowed, broadcast,
   brought to notice, certified, circulated, common knowledge,
   common property, conceded, confessed, confirmed, countersigned,
   current, declared, deposed, diffused, disseminated, distributed,
   endorsed, enunciated, granted, in circulation, in print,
   made public, manifestoed, notarized, open, pledged, predicated,
   proclaimed, professed, pronounced, propagated, public, published,
   ratified, received, recognized, reported, sealed, signed, spread,
   stamped, stated, sworn, sworn and affirmed, sworn to, telecast,
   televised, underwritten, validated, vouched, vouched for, vowed,
   warranted