whimsey
1. [ noun ] an odd or fanciful or capricious idea
Synonyms: notion whimsy whim
Examples:

"the theatrical notion of disguise is associated with disaster in his stories" "he had a whimsy about flying to the moon" "whimsy can be humorous to someone with time to enjoy it"

Related terms: idea
2. [ noun ] the trait of acting unpredictably and more from whim or caprice than from reason or judgment
Synonyms: arbitrariness whimsicality whimsy capriciousness flightiness
Examples:

"I despair at the flightiness and whimsicality of my memory"

Related terms: irresponsibility
Similar spelling:   whimsy