The Collaborative International Dictionary of English v.0.48:

refute \re*fute"\ (r[-e]*f[=u]t"), v. t. [imp. & p. p.
   Refuted; p. pr. & vb. n. Refuting.] [F. r['e]futer, L.
   refuteare to repel, refute. Cf. Confute, Refuse to deny.]
   To disprove and overthrow by argument, evidence, or
   countervailing proof; to prove to be false or erroneous; to
   confute; as, to refute arguments; to refute testimony; to
   refute opinions or theories; to refute a disputant.
   [1913 Webster]

         There were so many witnesses in these two miracles that
         it is impossible to refute such multitudes. --Addison.
   [1913 Webster]

   Syn: To confute; disprove. See Confute.
        [1913 Webster]

WordNet (r) 3.0 (2006):

refute
    v 1: overthrow by argument, evidence, or proof; "The speaker
         refuted his opponent's arguments" [syn: refute, rebut]
    2: prove to be false or incorrect [syn: refute, rebut,
       controvert]

Moby Thesaurus II by Grady Ward, 1.0:

94 Moby Thesaurus words for "refute":
   abjure, advocate, allege in support, answer, answer conclusively,
   argue down, argue for, assert, assert the contrary, belie, break,
   champion, confound, confute, contend for, contest, contradict,
   contravene, controvert, counter, countercharge, counterclaim,
   cross, crush, defeat, defend, demolish, deny, disaffirm, disallow,
   disavow, disclaim, disconfirm, dismiss, disown, dispose of,
   disprove, dispute, espouse, evert, finish, floor, forswear,
   gainsay, impugn, join issue upon, maintain, make a plea,
   make a rebuttal, nonplus, not accept, not admit, nullify, oppose,
   overthrow, overturn, overwhelm, parry, plead for, put to silence,
   rebut, recant, reduce to silence, refuse to admit, rejoin,
   renounce, reply, repudiate, respond, retract, revoke, riposte,
   say in defense, settle, shut up, silence, smash all opposition,
   speak for, speak up for, squash, squelch, stand up for,
   stick up for, subvert, support, surrebut, surrejoin, sustain,
   take back, take issue with, undermine, uphold, upset,
   urge reasons for