Source : Webster's Revised Unabridged Dictionary (1913)

Righteousness \Right"eous*ness\, n. [AS. rihtw[=i]snes.]
   1. The quality or state of being righteous; holiness; purity;
      uprightness; rectitude.

   Note: Righteousness, as used in Scripture and theology, in
         which it chiefly occurs, is nearly equivalent to
         holiness, comprehending holy principles and affections
         of heart, and conformity of life to the divine law.

   2. A righteous act, or righteous quality.

            All our righteousnesses are as filthy rags. --Isa.
                                                  lxiv. 6.

   3. The act or conduct of one who is righteous.

            Blessed are they that keep judgment, and he that
            doeth righteousness at all times.     --Ps. cvi. 3.

   4. (Theol.) The state of being right with God; justification;
      the work of Christ, which is the ground of justification.

            There are two kinds of Christian righteousness: the
            one without us, which we have by imputation; the
            other in us, which consisteth of faith, hope, and
            charity, and other Christian virtues. --Hooker.

            Only for the righteousness of Christ imputed to us,
            and received by faith alone.          --Westminster
                                                  Catechism.

   Syn: Uprightness; holiness; godliness; equity; justice;
        rightfulness; integrity; honesty; faithfulness.

Source : WordNet®

righteousness
     n : adhering to moral principles [ant: {unrighteousness}]