sadistic

from WordNet (r) 3.0 (2006)

sadistic
    adj 1: deriving pleasure or sexual gratification from inflicting
           pain on another [ant: {masochistic}]

from Moby Thesaurus II by Grady Ward, 1.0

50 Moby Thesaurus words for "sadistic":
      Draconian, Tartarean, animal, anthropophagous, atrocious, barbaric,
      barbarous, beastly, bestial, bloodthirsty, bloody, bloody-minded,
      brutal, brutalized, brute, brutish, cannibalistic, cruel,
      cruel-hearted, demoniac, demoniacal, devilish, diabolic, fell,
      feral, ferocious, fiendish, fiendlike, fierce, hellish, infernal,
      inhuman, inhumane, monstrous, murderous, perverse, ruthless,
      sanguinary, sanguineous, satanic, savage, sharkish, slavering,
      subhuman, truculent, unchristian, uncivilized, unhuman, vicious,
      wolfish