The Collaborative International Dictionary of English v.0.48:

favor \fa"vor\ (f[=a]"v[~e]r), n. [Written also favour.] [OF.
   favor, F. faveur, L. favor, fr. favere to be favorable, cf.
   Skr. bh[=a]vaya to further, foster, causative of bh[=u] to
   become, be. Cf. Be. In the phrase to curry favor, favor is
   prob. for favel a horse. See 2d Favel.]
   1. Kind regard; propitious aspect; countenance; friendly
      disposition; kindness; good will.
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            Hath crawled into the favor of the king. --Shak.
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   2. The act of countenancing, or the condition of being
      countenanced, or regarded propitiously; support;
      promotion; befriending.
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            But found no favor in his lady's eyes. --Dryden.
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            And Jesus increased in wisdom and stature, and in
            favor with God and man.               --Luke ii. 52.
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   3. A kind act or office; kindness done or granted;
      benevolence shown by word or deed; an act of grace or good
      will, as distinct from justice or remuneration.
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            Beg one favor at thy gracious hand.   --Shak.
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   4. Mildness or mitigation of punishment; lenity.
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            I could not discover the lenity and favor of this
            sentence.                             --Swift.
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   5. The object of regard; person or thing favored.
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            All these his wondrous works, but chiefly man,
            His chief delight and favor.          --Milton.
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   6. A gift or present; something bestowed as an evidence of
      good will; a token of love; a knot of ribbons; something
      worn as a token of affection; as, a marriage favor is a
      bunch or knot of white ribbons or white flowers worn at a
      wedding.
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            Wear thou this favor for me, and stick it in thy
            cap.                                  --Shak.
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   7. Appearance; look; countenance; face. [Obs.]
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            This boy is fair, of female favor.    --Shak.
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   8. (Law) Partiality; bias. --Bouvier.
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   9. A letter or epistle; -- so called in civility or
      compliment; as, your favor of yesterday is received.
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   10. pl. Love locks. [Obs.] --Wright.
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   Challenge to the favor or Challenge for favor (Law), the
      challenge of a juror on grounds not sufficient to
      constitute a principal challenge, but sufficient to give
      rise to a probable suspicion of favor or bias, such as
      acquaintance, business relation, etc. See Principal
      challenge, under Challenge.

   In favor of, upon the side of; favorable to; for the
      advantage of.

   In favor with, favored, countenanced, or encouraged by.

   To curry favor [see the etymology of Favor, above], to
      seek to gain favor by flattery, caresses, kindness, or
      officious civilities.

   With one's favor, or By one's favor, with leave; by kind
      permission.
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            But, with your favor, I will treat it here.
                                                  --Dryden.

   Syn: Kindness; countenance; patronage; support; lenity;
        grace; gift; present; benefit.
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Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "in favor of":
   advocating, all for, approving, backing, favorable, favoring, for,
   in aid of, in behalf of, in furtherance of, on account of,
   on behalf of, pro, remedial of, supporting, well-disposed,
   well-inclined, with