caprice

1.	a sudden or unpredictable change of attitude, behaviour, etc; whim
2.	a tendency to such changes

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 ) .

Origin:
1660–70; < French < Italian; see capriccio

Synonyms
1. vagary, notion, whim, fancy.