a sudden, unpredictable change, as of one's mind or the weather.

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.

Music . capriccio ( def. 1 ) .

noun

constancy , constant , dependability , steadfastness

noun

bee * , caper * , changeableness , contrariety , crotchet , fad , fancy , fickleness , fitfulness , fool notion , freak , gag * , humor , impulse , inconsistency , inconstancy , jerk , kink , mood , notion , peculiarity , perversity , put on * , quirk , rib * , temper , thought , vagary , vein , whim , whimsy , bee , boutade , conceit , megrim , antic , capriccio , craze , inconsistent , sudden , trait , whimsey , willfulness