WordWeb Online

1. An odd or fanciful or capricious idea
   "the theatrical whimsey of disguise is associated with disaster in his stories"
   - notion, whim, whimsy
    
2. The trait of acting unpredictably and more from whim or caprice than from reason or judgment
   "I despair at the whimsey and whimsicality of my memory"
   - flightiness, arbitrariness, whimsicality, whimsy, capriciousness

Derived forms: whimseys

Type of: idea, irresponsibility, irresponsibleness, thought