WordNet (r) 3.0 (2006):

sadism
    n 1: sexual pleasure obtained by inflicting harm (physical or
         psychological) on others

Moby Thesaurus II by Grady Ward, 1.0:

67 Moby Thesaurus words for "sadism":
   active algolagnia, algolagnia, algolagny, amphierotism, animality,
   atrociousness, autoeroticism, barbarity, barbarousness,
   beastliness, bestiality, bisexuality, bloodiness, bloodlust,
   bloodthirst, bloodthirstiness, bloody-mindedness, brutality,
   brutalness, brutishness, cannibalism, coprophilia, cruelness,
   cruelty, exhibitionism, ferociousness, ferocity, fetishism,
   fiendishness, fierceness, heterosexuality, homoeroticism,
   homosexualism, homosexuality, incest, incestuousness, inhumaneness,
   inhumanity, lesbianism, masochism, narcissism, necrophilia,
   paraphilia, passive algolagnia, pedophilia, ruthlessness,
   sadistic cruelty, sadomasochism, sanguineousness, sapphism,
   savagery, scotophilia, sexual inversion, sexual normality,
   sexual preference, swinging both ways, transvestitism, tribadism,
   tribady, truculence, vandalism, viciousness, violence, voyeurism,
   wanton cruelty, zooerastia, zoophilia