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.
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            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):

disfavour
    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]