The Collaborative International Dictionary of English v.0.48:

Disparage \Dis*par"age\ (?; 48), v. t. [imp. & p. p.
   Disparaged; p. pr. & vb. n. Disparaging.] [OF.
   desparagier, F. d['e]parager, to marry unequally; pref. des-
   (L. dis-) + F. parage extraction, lineage, from L. par equal,
   peer. See Peer.]
   1. To match unequally; to degrade or dishonor by an unequal
      marriage. [Obs.]
      [1913 Webster]

            Alas! that any of my nation
            Should ever so foul disparaged be.    --Chaucer.
      [1913 Webster]

   2. To dishonor by a comparison with what is inferior; to
      lower in rank or estimation by actions or words; to speak
      slightingly of; to depreciate; to undervalue.
      [1913 Webster]

            Those forbidding appearances which sometimes
            disparage the actions of men sincerely pious. --Bp.
                                                  Atterbury.
      [1913 Webster]

            Thou durst not thus disparage glorious arms.
                                                  --Milton.

   Syn: To decry; depreciate; undervalue; underrate; cheapen;
        vilify; reproach; detract from; derogate from; degrade;
        debase. See Decry.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

disparaging \disparaging\ adj.
   expressing a low opinion of; same as derogatory; as,
   disparaging remarks about the new house.

   Syn: belittling, depreciative, deprecatory, depreciatory,
        derogative, derogatory, detractive, detracting,
        slighting, pejorative, denigratory.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

disparaging
    adj 1: expressive of low opinion; "derogatory comments";
           "disparaging remarks about the new house" [syn:
           derogative, derogatory, disparaging]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "disparaging":
   abusive, aweless, back-biting, belittling, bitchy, blackening,
   blameful, calumniatory, calumnious, catty, censorious,
   condemnatory, contemptuous, contumelious, damnatory, defamatory,
   denunciatory, deprecative, deprecatory, depreciative, depreciatory,
   derisive, derisory, derogative, derogatory, detracting, detractory,
   disadvantageous, discourteous, disrespectful, execrating,
   execrative, execratory, impudent, insolent, invective, inveighing,
   irreverent, judgmental, libelous, minimizing, objurgatory,
   pejorative, priggish, reproachful, reprobative, reviling,
   ridiculing, scandalous, scoffing, scurrile, scurrilous, slanderous,
   slighting, uncomplimentary, underrating, undervaluing, vilifying,
   vituperative