Example : 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.

Synonyms : notion, whim, whimsy

Example : I despair at the flightiness and whimsicality of my memory.

Synonyms : arbitrariness, capriciousness, flightiness, whimsicality, whimsy