Source : Webster's Revised Unabridged Dictionary (1913)

Disadvantage \Dis`ad*van"tage\, v. t. [Cf. F. d['e]savantager.]
   To injure the interest of; to be detrimental to.

Disadvantage \Dis`ad*van"tage\ (?; 48, 61), n. [Cf. F.
   d['e]savantage.]
   1. Deprivation of advantage; unfavorable or prejudicial
      quality, condition, circumstance, or the like; that which
      hinders success, or causes loss or injury.

            I was brought here under the disadvantage of being
            unknown by sight to any of you.       --Burke.

            Abandoned by their great patron, the faction
            henceforward acted at disadvantage.   --Palfrey.

   2. Loss; detriment; hindrance; prejudice to interest, fame,
      credit, profit, or other good.

            They would throw a construction on his conduct, to
            his disadvantage before the public.   --Bancroft.

   Syn: Detriment; injury; hurt; loss; damage.

Source : WordNet®

disadvantage
     n : the quality of having an inferior or less favorable position
         [ant: {advantage}]

disadvantage
     v : put at a disadvantage; hinder, harm; "This rule clearly
         disadvantages me" [syn: {disfavor}, {disfavour}] [ant: {advantage}]