Source : Webster's Revised Unabridged Dictionary (1913)

Ill-natured \Ill`-na"tured\, a.
   1. Of habitual bad temper; peevish; fractious; cross;
      crabbed; surly; as, an ill-natured person.

   2. Dictated by, or indicating, ill nature; spiteful. ``The
      ill-natured task refuse.'' --Addison.

   3. Intractable; not yielding to culture. [R.] ``Ill-natured
      land.'' --J. Philips. -- {Ill`-na"tured*ly}, adv. --
      {Ill`-na"tured*ness}, n.

Source : WordNet®

ill-natured
     adj : having an irritable and unpleasant disposition; "an
           ill-natured disagreeable old man" [ant: {good-natured}]