Source : Webster's Revised Unabridged Dictionary (1913)

Capricious \Ca*pri"cious\, a. [Cf. F. capricleux, It.
   capriccioso.]
   Governed or characterized by caprice; apt to change suddenly;
   freakish; whimsical; changeable. ``Capricious poet.'' --Shak.
   ``Capricious humor.'' --Hugh Miller.

         A capricious partiality to the Romish practices.
                                                  --Hallam.

   Syn: Freakish; whimsical; fanciful; fickle; crotchety;
        fitful; wayward; changeable; unsteady; uncertain;
        inconstant; arbitrary. -- {Ca*pri"cious*ly}, adv. --
        {Ca*pri"cious*ness}, n.

Source : WordNet®

capriciousness
     n 1: the quality of being guided by sudden unpredictable impulses
          [syn: {unpredictability}]
     2: the trait of acting unpredictably and more from whim or
        caprice than from reason or judgment; "I despair at the
        flightiness and whimsicality of my memory" [syn: {flightiness},
         {arbitrariness}, {whimsicality}, {whimsy}, {whimsey}]