The Collaborative International Dictionary of English v.0.48:

Caprice \Ca*price"\ (k[.a]*pr[=e]s"), n. [F. caprice, It.
   capriccio, caprice (perh. orig. a fantastical goat leap), fr.
   L. caper, capra, goat. Cf Capriole, Cab, Caper, v. i.]
   1. An abrupt change in feeling, opinion, or action,
      proceeding from some whim or fancy; a freak; a notion.
      "Caprices of appetite." --W. Irving.
      [1913 Webster]

   2. (Mus.) See Capriccio.

   Syn: Freak; whim; crotchet; fancy; vagary; humor; whimsey;
        fickleness.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Capriccio \Ca*pric"cio\ (k[.a]*pr[=e]t"ch[-o]), n. [It. See
   Caprice.]
   1. (Mus.) A piece in a free form, with frequent digressions
      from the theme; a fantasia; -- often called caprice.
      [1913 Webster]

   2. A caprice; a freak; a fancy. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

caprice
    n 1: a sudden desire; "he bought it on an impulse" [syn:
         caprice, impulse, whim]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "caprice":
   arbitrariness, bee, boutade, capriccio, capriciousness,
   carelessness, characteristic, conceit, contrariety, crank,
   crankiness, crotchet, crotchetiness, divertissement, fancifulness,
   fancy, fantasia, fantasticality, foible, freak, freakishness,
   habit, heedlessness, humor, humoresque, humorsomeness,
   inconsiderateness, inconsideration, inconsistency, maggot,
   mannerism, medley, megrim, mood, moodiness, motivelessness, notion,
   peculiarity, perversity, petulance, potpourri, quirkiness, romance,
   romanza, temper, temperamentalness, thoughtlessness, trait, trick,
   unthoughtfulness, vagary, vein, whim, whimsicality, whimsicalness,
   whimsy