Synonyms for Whimsicality (same or very similar meaning)
WordNet sense 1 (the trait of acting unpredictably and more from whim or caprice than from reason or judgment):
arbitrariness, capriciousness, flightiness, whimsey, whimsyWordNet sense 2 (the trait of behaving like an imp):
impishness, mischievousness, puckishnessFrom the ODE community, based on WordNetadd/edit