flightiness vs whimsey

flightiness and whimsey both are nouns.

Word	Noun	Adjective	Verb	Adverb
flightiness	Yes	No	No	No
whimsey	Yes	No	No	No

As nouns, flightiness and whimsey are synonyms defined as:

flightiness and whimsey: the trait of acting unpredictably and more from whim or caprice than from reason or judgment

Other synonyms of flightiness include arbitrariness, capriciousness, whimsicality, whimsy.

flightiness (noun)	whimsey (noun)
the trait of acting unpredictably and more from whim or caprice than from reason or judgment	the trait of acting unpredictably and more from whim or caprice than from reason or judgment
	an odd or fanciful or capricious idea