inhumane

from WordNet (r) 3.0 (2006)

inhumane
    adj 1: lacking and reflecting lack of pity or compassion;
           "humans are innately inhumane; this explains much of the
           misery and suffering in the world"; "biological weapons
           are considered too inhumane to be used" [ant: {humane}]

from The Collaborative International Dictionary of English v.0.48

inhumane \in`hu*mane"\ ([i^]n`h[=u]*m[=a]n"), adj.
   not humane; lacking and reflecting lack of pity, kindness, or
   compassion; as, humans are innately inhumane; this explains
   much of the misery and suffering in the world; biological
   weapons are considered too inhumane to be used. [Narrower