fugaciousness vs fugacity

fugaciousness and fugacity both are nouns.

Word	Noun	Adjective	Verb	Adverb
fugaciousness	Yes	No	No	No
fugacity	Yes	No	No	No

As nouns, fugaciousness and fugacity are synonyms defined as:

fugaciousness and fugacity: the lack of enduring qualities (used chiefly of plant parts)

fugaciousness (noun)	fugacity (noun)
the lack of enduring qualities (used chiefly of plant parts)	the lack of enduring qualities (used chiefly of plant parts)
	the tendency of a gas to expand or escape