The Collaborative International Dictionary of English v.0.48:

deflower \de*flow"er\, v. t. [Previously also spelled
   deflour.] [imp. & p. p. Deflowered; p. pr. & vb. n.
   Deflowering.] [F. d['e]florer, LL. deflorare; L. de- +
   flos, floris, flower. See Flower, and cf. Deflorate.]
   1. To deprive of flowers.
      [1913 Webster]

            An earthquake . . . deflowering the gardens. --W.
                                                  Montagu.
      [1913 Webster]

   2. To take away the prime beauty and grace of; to rob of the
      choicest ornament.
      [1913 Webster]

   3. To deprive of virginity, as a woman; to violate; to
      ravish; also, to seduce.
      [1913 Webster]

            If a man had deflowered a virgin.     --Milton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

deflower
    v 1: deprive of virginity; "This dirty old man deflowered
         several young girls in the village" [syn: deflower,
         ruin]
    2: make imperfect; "nothing marred her beauty" [syn: mar,
       impair, spoil, deflower, vitiate]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "deflower":
   abuse, adulterate, alloy, assault sexually, betray, canker,
   cheapen, coarsen, confound, contaminate, corrupt, debase, debauch,
   deceive, defile, deflorate, degenerate, degrade, denature, deprave,
   depredate, desecrate, desolate, despoil, devalue, devastate,
   devirginate, devour, distort, force, harry, havoc, infect,
   lead astray, mislead, misuse, outrage, pervert, poison, pollute,
   possess sexually, prostitute, rape, ravage, ravish, ruin, seduce,
   soil, spoil, sully, taint, take, twist, ulcerate, violate, vitiate,
   vulgarize, warp