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" - flightiness, arbitrariness, whimsy, whimsey, capriciousness
The trait of behaving like an imp - impishness, mischievousness, puckishness
Derived forms: whimsicalities
See also: whimsical
Type of: fun, irresponsibility, irresponsibleness, playfulness