The Collaborative International Dictionary of English v.0.48:

Deprave \De*prave"\ (d[-e]*pr[=a]v"), v. t. [imp. & p. p.
   Depraved (d[-e]*pr[=a]vd"); p. pr. & vb. n. Depraving.]
   [L. depravare, depravatum; de- + pravus crooked, distorted,
   perverse, wicked.]
   1. To speak ill of; to depreciate; to malign; to revile.
      [Obs.]
      [1913 Webster]

            And thou knowest, conscience, I came not to chide
            Nor deprave thy person with a proud heart. --Piers
                                                  Plowman.
      [1913 Webster]

   2. To make bad or worse; to vitiate; to corrupt.
      [1913 Webster]

            Whose pride depraves each other better part.
                                                  --Spenser.

   Syn: To corrupt; vitiate; contaminate; pollute.
        [1913 Webster]

WordNet (r) 3.0 (2006):

deprave
    v 1: corrupt morally or by intemperance or sensuality; "debauch
         the young people with wine and women"; "Socrates was
         accused of corrupting young men"; "Do school counselors
         subvert young children?"; "corrupt the morals" [syn:
         corrupt, pervert, subvert, demoralize,
         demoralise, debauch, debase, profane, vitiate,
         deprave, misdirect]

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "deprave":
   abuse, adulterate, afflict, aggrieve, alloy, bastardize, befoul,
   bewitch, blight, brutalize, canker, cheapen, coarsen, condemn,
   confound, contaminate, corrupt, crucify, curse, damage, debase,
   debauch, defile, deflower, degenerate, degrade, demoralize,
   denature, desecrate, despoil, destroy, devalue, disadvantage,
   disserve, distort, distress, do a mischief, do evil, do ill,
   do wrong, do wrong by, doom, envenom, get into trouble, harass,
   harm, hex, hurt, impair, infect, injure, jinx, maltreat, menace,
   mistreat, misuse, molest, outrage, persecute, pervert,
   play havoc with, play hob with, poison, pollute, prejudice,
   prostitute, ravage, ravish, savage, scathe, taint, threaten,
   torment, torture, twist, ulcerate, violate, vitiate, vulgarize,
   warp, wound, wreak havoc on, wrong