subhuman

subhuman
    adj 1: less than human or not worthy of a human being; "treated
           natives as subhuman"; "a subhuman spectacle"; "the
           subhuman primates" [ant: {superhuman}]
    2: unfit for human beings; "subhuman conditions of life"
    

61 Moby Thesaurus words for "subhuman":
      Draconian, Tartarean, animal, animalian, animalic, animalistic,
      anthropophagous, atrocious, barbaric, barbarous, beastlike,
      beastly, bestial, bloodthirsty, bloody, bloody-minded, brutal,
      brutalized, brute, brutelike, brutish, cannibalistic, cruel,
      cruel-hearted, demoniac, demoniacal, devilish, diabolic, dumb,
      fell, feral, ferocious, fiendish, fiendlike, fierce, hellish,
      infernal, inhuman, inhumane, instinctive, instinctual, mindless,
      murderous, nonrational, ruthless, sadistic, sanguinary,
      sanguineous, satanic, savage, sharkish, slavering, truculent,
      unchristian, uncivilized, unhuman, vicious, wolfish, zoic, zooidal,
      zoologic