The Collaborative International Dictionary of English v.0.48:

Disfavor \Dis*fa"vor\, v. t. [imp. & p. p. Disfavored; p. pr.
   & vb. n. Disfavoring.]
   1. To withhold or withdraw favor from; to regard with
      disesteem; to show disapprobation of; to discountenance.
      [1913 Webster]

            Countenanced or disfavored according as they obey.
                                                  --Swift.
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   2. To injure the form or looks of. [R.] --B. Jonson.
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The Collaborative International Dictionary of English v.0.48:

Disfavor \Dis*fa"vor\, n. [Pref. dis- + favor: cf. OF.
   disfaveur, F. d['e]faveur.] [Written also disfavour.]
   1. Want of favor of favorable regard; disesteem; disregard.
      [1913 Webster]

            The people that deserved my disfavor. --Is. x. 6
                                                  (1551).
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            Sentiment of disfavor against its ally. --Gladstone.
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   2. The state of not being in favor; a being under the
      displeasure of some one; state of unacceptableness; as, to
      be in disfavor at court.
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   3. An unkindness; a disobliging act.
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            He might dispense favors and disfavors. --Clarendon.
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WordNet (r) 3.0 (2006):

disfavor
    n 1: the state of being out of favor; "he is in disfavor with
         the king" [syn: disfavor, disfavour]
    2: an inclination to withhold approval from some person or group
       [syn: disfavor, disfavour, dislike, disapproval]
    v 1: put at a disadvantage; hinder, harm; "This rule clearly
         disadvantages me" [syn: disadvantage, disfavor,
         disfavour] [ant: advantage]

Moby Thesaurus II by Grady Ward, 1.0:

126 Moby Thesaurus words for "disfavor":
   abhor, alienation, aversion, bad books, bad character, bad name,
   bad odor, bad report, bad reputation, bad repute, ban,
   be hostile to, blackball, blackballing, breach,
   breach of friendship, break, categorically reject, cleavage, cleft,
   complaint, deprecate, dim view, disaffection, disaffinity,
   disagreement, disallow, disappointment, disapprobation,
   disapproval, disapprove, disapprove of, discommend, discontent,
   discontentedness, discontentment, discountenance, discredit,
   disenchantment, disesteem, disgrace, disgruntlement, dishonor,
   disillusion, disillusionment, disinclination, dislike, disliking,
   displeasure, disrelish, disrepute, disrespect, disruption,
   dissatisfaction, dissent, dissent from, distaste, distrust,
   disunion, disunity, divergence, dividedness, division,
   estrangement, evil repute, exclude, exclusion, falling-out, frown,
   frown at, frown down, frown upon, grimace at, hate, ignominy,
   ill fame, ill repute, ill-favor, indignation, indisposition,
   infamy, loathe, look askance at, look black upon, low estimation,
   low opinion, mislike, mistrust, not approve, not care for,
   not go for, not hear of, not hold with, object, object to,
   objection, obloquy, odium, open rupture, oppose, opposition,
   opposure, opprobrium, ostracism, ostracize, poor reputation,
   protest, public dishonor, recall of ambassadors, reject, rejection,
   rift, rupture, say no to, schism, separation, shady reputation,
   split, take exception to, think ill of, think little of,
   thumb down, thumbs-down, unhappiness, unsavory reputation,
   view with disfavor