The Collaborative International Dictionary of English v.0.48:

Challenge \Chal"lenge\, n. [OE. chalenge claim, accusation,
   challenge, OF. chalenge, chalonge, claim, accusation,
   contest, fr. L. calumnia false accusation, chicanery. See
   Calumny.]
   1. An invitation to engage in a contest or controversy of any
      kind; a defiance; specifically, a summons to fight a duel;
      also, the letter or message conveying the summons.
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            A challenge to controversy.           --Goldsmith.
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   2. The act of a sentry in halting any one who appears at his
      post, and demanding the countersign.
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   3. A claim or demand. [Obs.]
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            There must be no challenge of superiority.
                                                  --Collier.
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   4. (Hunting) The opening and crying of hounds at first
      finding the scent of their game.
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   5. (Law) An exception to a juror or to a member of a court
      martial, coupled with a demand that he should be held
      incompetent to act; the claim of a party that a certain
      person or persons shall not sit in trial upon him or his
      cause. --Blackstone
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   6. An exception to a person as not legally qualified to vote.
      The challenge must be made when the ballot is offered. [U.
      S.]
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   Challenge to the array (Law), an exception to the whole
      panel.

   Challenge to the favor, the alleging a special cause, the
      sufficiency of which is to be left to those whose duty and
      office it is to decide upon it.

   Challenge to the polls, an exception taken to any one or
      more of the individual jurors returned.

   Peremptory challenge, a privilege sometimes allowed to
      defendants, of challenging a certain number of jurors
      (fixed by statute in different States) without assigning
      any cause.

   Principal challenge, that which the law allows to be
      sufficient if found to be true.
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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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