Source : Webster's Revised Unabridged Dictionary (1913)

Inimical \In*im"i*cal\ (?; 277), a. [L. inimicalis, fr. inimicus
   unfriendly, hostile; pref. in- not + amicus friendly. See
   {Amity}.]
   1. Having the disposition or temper of an enemy; unfriendly;
      unfavorable; -- chiefly applied to private, as hostile is
      to public, enmity.

   2. Opposed in tendency, influence, or effects; antagonistic;
      inconsistent; incompatible; adverse; repugnant.

            We are at war with a system, which, by its essence,
            is inimical to all other governments. --Burke.

Source : WordNet®

inimical
     adj : not friendly; "an unfriendly act of aggression"; "an
           inimical critic" [syn: {unfriendly}]