The Collaborative International Dictionary of English v.0.48:

Unhuman \Un*hu"man\, a.
   Not human; inhuman.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unhuman
    adj 1: divested of human qualities or attributes [syn:
           dehumanized, dehumanised, unhuman]

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "unhuman":
   Draconian, Tartarean, animal, anthropophagous, arcane, atrocious,
   barbaric, barbarous, beastly, bestial, bloodthirsty, bloody,
   bloody-minded, brutal, brutalized, brute, brutish, cannibalistic,
   cruel, cruel-hearted, demoniac, demoniacal, devilish, diabolic,
   eerie, esoteric, extramundane, extraterrestrial, fell, feral,
   ferocious, fey, fiendish, fiendlike, fierce, hellish, hypernormal,
   hyperphysical, infernal, inhuman, inhumane, murderous, mysterious,
   numinous, occult, otherworldly, preterhuman, preternatural,
   preternormal, pretersensual, psychic, ruthless, sadistic,
   sanguinary, sanguineous, satanic, savage, sharkish, slavering,
   spiritual, subhuman, superhuman, supernatural, supernormal,
   superphysical, supersensible, supersensual, supramundane,
   supranatural, transcendental, transmundane, truculent, unchristian,
   uncivilized, unearthly, unworldly, vicious, wolfish