Source : Webster's Revised Unabridged Dictionary (1913)

Inhuman \In*hu"man\, a. [L. inhumanus: cf. F. inhumain. See
   {In-} not, and {Human}.]
   1. Destitute of the kindness and tenderness that belong to a
      human being; cruel; barbarous; savage; unfeeling; as, an
      inhuman person or people.

   2. Characterized by, or attended with, cruelty; as, an
      inhuman act or punishment.

   Syn: Cruel; unfeeling; pitiless; merciless; savage;
        barbarous; brutal; ferocious; ruthless; fiendish.

Source : WordNet®

inhuman
     adj 1: without compunction or human feeling; "in cold blood";
            "cold-blooded killing"; "insensate destruction" [syn:
            {cold}, {cold-blooded}, {insensate}]
     2: belonging to or resembling something nonhuman; "something
        dark and inhuman in form"; "a babel of inhuman noises"