whim vs notion

whim and notion both are nouns.

Word	Noun	Adjective	Verb	Adverb
whim	Yes	No	No	No
notion	Yes	No	No	No

As nouns, whim and notion are synonyms defined as:

Other synonyms of whim include whimsey, whimsy.

whim (noun)	notion (noun)
an odd or fanciful or capricious idea	(usually plural) small personal articles or clothing or sewing items
a sudden desire	a general inclusive concept
	an odd or fanciful or capricious idea
	a vague idea in which some confidence is placed