The Collaborative International Dictionary of English v.0.48:

Disdain \Dis*dain"\ (?; 277), n. [OE. desdain, disdein, OF.
   desdein, desdaing, F. d['e]dain, fr. the verb. See Disdain,
   v. t.]
   1. A feeling of contempt and aversion; the regarding anything
      as unworthy of or beneath one; scorn.
      [1913 Webster]

            How my soul is moved with just disdain! --Pope.
      [1913 Webster]

   Note: Often implying an idea of haughtiness.
         [1913 Webster]

               Disdain and scorn ride sparkling in her eyes.
                                                  --Shak.
         [1913 Webster]

   2. That which is worthy to be disdained or regarded with
      contempt and aversion. [Obs.]
      [1913 Webster]

            Most loathsome, filthy, foul, and full of vile
            disdain.                              --Spenser.
      [1913 Webster]

   3. The state of being despised; shame. [Obs.] --Shak.

   Syn: Haughtiness; scorn; contempt; arrogance; pride. See
        Haughtiness.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disdain \Dis*dain"\ (?; 277), v. t. [imp. & p. p. Disdained;
   p. pr. & vb. n. Disdaining.] [OE. disdainen, desdainen, OF.
   desdeigner, desdaigner, F. d['e]daigner; des- (L. dis-) +
   daigner to deign, fr. L. dignari to deem worthy. See
   Deign.]
   1. To think unworthy; to deem unsuitable or unbecoming; as,
      to disdain to do a mean act.
      [1913 Webster]

            Disdaining . . . that any should bear the armor of
            the best knight living.               --Sir P.
                                                  Sidney.
      [1913 Webster]

   2. To reject as unworthy of one's self, or as not deserving
      one's notice; to look with scorn upon; to scorn, as base
      acts, character, etc.
      [1913 Webster]

            When the Philistine . . . saw David, he disdained
            him; for he was but a youth.          --1 Sam. xvii.
                                                  42.
      [1913 Webster]

            'T is great, 't is manly to disdain disguise.
                                                  --Young.

   Syn: To contemn; despise; scorn. See Contemn.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disdain \Dis*dain"\, v. i.
   To be filled with scorn; to feel contemptuous anger; to be
   haughty.
   [1913 Webster]

         And when the chief priests and scribes saw the marvels
         that he did . . . they disdained.        --Genevan
                                                  Testament
                                                  (Matt. xxi.
                                                  15).
   [1913 Webster]

WordNet (r) 3.0 (2006):

disdain
    n 1: lack of respect accompanied by a feeling of intense
         dislike; "he was held in contempt"; "the despite in which
         outsiders were held is legendary" [syn: contempt,
         disdain, scorn, despite]
    2: a communication that indicates lack of respect by patronizing
       the recipient [syn: condescension, disdain, patronage]
    v 1: look down on with disdain; "He despises the people he has
         to work for"; "The professor scorns the students who don't
         catch on immediately" [syn: contemn, despise, scorn,
         disdain]
    2: reject with contempt; "She spurned his advances" [syn:
       reject, spurn, freeze off, scorn, pooh-pooh,
       disdain, turn down]

Moby Thesaurus II by Grady Ward, 1.0:

152 Moby Thesaurus words for "disdain":
   abhor, abjure, airs, antipathetic, antipathy, aristocratic disdain,
   arrogance, arrogant, audacity, averse, aversion, be above,
   be contemptuous of, bold front, boldness, brash bearing, brashness,
   brassiness, bravado, brazenness, brush aside, bumptiousness,
   care nothing for, cavalier, cavalierness, cheekiness, chuck,
   chuck out, clannishness, cliquishness, cockiness, contemn,
   contempt, contemptuousness, contradict, contumeliousness,
   contumely, daring, daringness, decline, defial, defiance, defying,
   denigrate, deny, deprecate, depreciate, deride, derision, despisal,
   despise, despising, despite, disapprove, discard, disclaim,
   discommend, discount, disdainful, disdainfulness, dismiss, disown,
   disparage, disparagement, dispraise, disprize, disregard, disvalue,
   dump on, except, exclude, exclusiveness, feel contempt for,
   feel superior to, flout, forswear, fuss, haughtiness, haughty,
   hauteur, high-and-mighty, hold beneath one, hold cheap,
   hold in contempt, hold in derision, ignore, impertinence,
   impudence, insolence, insolent, insult, laugh at, laugh to scorn,
   loftiness, look down upon, lordly, misprize, morgue, overbearing,
   pass by, pass up, pertness, pick and choose, push aside, put down,
   rank low, rebuff, recant, refuse, refuse to consider, reject,
   rejecting, renounce, repel, repudiate, repulse, ridicule,
   sauciness, scoff at, scorn, scornfulness, scorning, scout,
   scouting, set at defiance, set at naught, shove away, slight,
   slight over, sneer at, sneeze at, sniff at, sniffiness,
   snobbishness, snootiness, snort at, snottiness, sovereign contempt,
   spurn, spurning, supercilious, superciliousness, superior,
   think nothing of, throw away, throw out, toploftiness,
   treat with contempt, turn away, turn out, unsympathetic, waive