Source : Webster's Revised Unabridged Dictionary (1913)

Unrighteous \Un*right"eous\, a. [OE. unrightwise, AS.
   unrihtw[=i]s. See {Un-} not, and {Righteous}.]
   1. Not righteous; evil; wicked; sinful; as, an unrighteous
      man.

   2. Contrary to law and equity; unjust; as, an unrighteous
      decree or sentence. -- {Un*right"eous*ly}, adv. --
      {Un*right"eous*ness}, n.

Source : WordNet®

unrighteous
     adj : not righteous; "an unrighteous man"; "an unrighteous law"
           [ant: {righteous}]