from Dictionary.com:

CA·PRICE [kuh-prees]
-noun
   1. a sudden, unpredictable change, as of one's mind or the weather.
   2. a tendency to change one's mind without apparent or adequate motive; whimsicality; capriciousness: With the caprice of a despotic king, he alternated between kindness and cruelty.
   3. Music. CAPRICCIO (def. 1).
                                  -> a composition in a free, irregular style.

--Synonyms: valgary, notion, whim, fancy.