The Collaborative International Dictionary of English v.0.48:

Unjust \Un*just"\, a.
   1. Acting contrary to the standard of right; not animated or
      controlled by justice; false; dishonest; as, an unjust man
      or judge.
      [1913 Webster]

   2. Contrary to justice and right; prompted by a spirit of
      injustice; wrongful; as, an unjust sentence; an unjust
      demand; an unjust accusation.
      [1913 Webster] -- Un*just"ly, adv. -- Un*just"ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unjustness
    n 1: the practice of being unjust or unfair [syn: injustice,
         unjustness] [ant: justice, justness]