Whimsey

n.	1.	A whim; a freak; a capricious notion, a fanciful or odd conceit. Men's folly, whimsies, and inconstancy. - Swift. Mistaking the whimseys of a feverish brain for the calm revelation of truth. - Bancroft.
	2.	(Mining) A whim.
v. t.	1.	To fill with whimseys, or whims; to make fantastic; to craze. To have a man's brain whimsied with his wealth. - J. Fletcher.

Noun	1.	whimsey - an odd or fanciful or capricious idea; "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: whimsy, whim, notion
	2.	whimsey - 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" Synonyms: arbitrariness, flightiness, whimsicality, whimsy, capriciousness

idea, notion, thought, whim, whimsy