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):

depraved
    adj 1: deviating from what is considered moral or right or
           proper or good; "depraved criminals"; "a perverted sense
           of loyalty"; "the reprobate conduct of a gambling
           aristocrat" [syn: depraved, perverse, perverted,
           reprobate]

Moby Thesaurus II by Grady Ward, 1.0:

80 Moby Thesaurus words for "depraved":
   abandoned, abject, abominable, arrant, atrocious, base, beggarly,
   cheesy, contaminated, contemptible, corrupt, corrupted, crummy,
   debased, debauched, decadent, degenerate, degraded, despicable,
   dirty, disgusting, dissolute, execrable, flagitious, flagrant,
   foul, fulsome, grave, gross, heinous, infamous, little, low,
   low-down, lumpen, mangy, mean, measly, miscreant, miserable,
   monstrous, morally polluted, nefarious, obnoxious, odious, paltry,
   perverse, perverted, petty, poky, polluted, poor, profligate,
   putrid, rank, reprobate, reptilian, rotten, scabby, scrubby,
   scruffy, scummy, scurvy, shabby, shoddy, small, squalid,
   steeped in iniquity, tainted, twisted, unhealthy, unmentionable,
   vice-corrupted, vicious, vile, villainous, vitiate, vitiated,
   warped, wretched