Source : Webster's Revised Unabridged Dictionary (1913)

Villainous \Vil"lain*ous\, a. [Written also villanous.]
   1. Base; vile; mean; depraved; as, a villainous person or
      wretch.

   2. Proceeding from, or showing, extreme depravity; suited to
      a villain; as, a villainous action.

   3. Sorry; mean; mischievous; -- in a familiar sense. ``A
      villainous trick of thine eye.'' --Shak.

   {Villainous judgment} (O. E. Law), a judgment that casts
      reproach on the guilty person. --- {Vil"lain*ous*ly}, adv.
      {Vil"lain*ous*ness}, n.

Source : WordNet®

villainous
     adj : extremely wicked; "nefarious schemes"; "a villainous plot";
           "a villainous band of thieves" [syn: {nefarious}]