fleetingness vs ephemeralness

fleetingness and ephemeralness both are nouns.

Word	Noun	Adjective	Verb	Adverb
fleetingness	Yes	No	No	No
ephemeralness	Yes	No	No	No

As nouns, fleetingness and ephemeralness are synonyms defined as:

fleetingness and ephemeralness: the property of lasting for a very short time

Other synonyms of fleetingness include ephemerality.

fleetingness (noun)	ephemeralness (noun)
the property of lasting for a very short time	the property of lasting for a very short time