Source : Webster's Revised Unabridged Dictionary (1913)

Evenness \E"ven*ness\, n.
   The state of being ven, level, or disturbed; smoothness;
   horizontal position; uniformity; impartiality; calmness;
   equanimity; appropriate place or level; as, evenness of
   surface, of a fluid at rest, of motion, of dealings, of
   temper, of condition.

         It had need be something extraordinary, that must
         warrant an ordinary person to rise higher than his own
         evenness.                                --Jer. Taylor.

Source : WordNet®

evenness
     n 1: a quality of uniformity and lack of variation [syn: {invariability}]
          [ant: {unevenness}, {unevenness}]
     2: the quality of being balanced [ant: {unevenness}]