The Collaborative International Dictionary of English v.0.48:

Forswear \For*swear"\, v. t. [imp. Forswore; p. p. Forsworn;
   p. pr. & vb. n. Forswearing.] [OE. forsweren, forswerien,
   AS. forswerian; pref. for- + swerian to swear. See For-,
   and Swear, v. i.]
   1. To reject or renounce upon oath; hence, to renounce
      earnestly, determinedly, or with protestations.
      [1913 Webster]

            I . . . do forswear her.              --Shak.
      [1913 Webster]

   2. To deny upon oath.
      [1913 Webster]

            Like innocence, and as serenely bold
            As truth, how loudly he forswears thy gold!
                                                  --Dryden.
      [1913 Webster]

   To forswear one's self, to swear falsely; to perjure one's
      self. "Thou shalt not forswear thyself." --Matt. v. 33.

   Syn: See Perjure.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Forswear \For*swear"\, v. i.
   To swear falsely; to commit perjury. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

forswear
    v 1: formally reject or disavow a formerly held belief, usually
         under pressure; "He retracted his earlier statements about
         his religion"; "She abjured her beliefs" [syn: abjure,
         recant, forswear, retract, resile]

Moby Thesaurus II by Grady Ward, 1.0:

118 Moby Thesaurus words for "forswear":
   abandon, abdicate, abjure, acknowledge defeat, assert the contrary,
   back down, back out, backwater, belie, brush aside, cease, cede,
   chuck, chuck out, climb down, contemn, contest, contradict,
   contravene, controvert, counter, crawfish out, cross, cry quits,
   decline, deny, desist from, despise, disaffirm, disallow,
   disapprove, disavow, discard, disclaim, discontinue, discount,
   disdain, disgorge, dismiss, disown, dispense with, dispose of,
   disprove, dispute, disregard, do without, drop, dump, eat crow,
   eat humble pie, except, exclude, forgo, gainsay, get along without,
   get rid of, give away, give over, give up, hand over,
   have done with, ignore, impugn, join issue upon, kiss good-bye,
   lay down, leave off, make a sacrifice, not accept, not admit,
   nullify, oppose, palinode, part with, pass by, pass up, push aside,
   quitclaim, rebuff, recall, recant, refuse, refuse to admit,
   refuse to consider, refute, reject, relinquish, render up, renege,
   renounce, repel, repudiate, repulse, resign, retract, revoke,
   sacrifice, scout, shove away, spare, spurn, stop, surrender,
   swallow, swear off, take back, take issue with, take the pledge,
   throw away, throw out, throw up, turn away, turn out, unsay,
   vacate, waive, withdraw, yield