inactive vs inactiveness

inactive is not a noun while inactiveness is a noun.

Word	Noun	Adjective	Verb	Adverb
inactive	No	Yes	No	No
inactiveness	Yes	No	No	No

inactive (noun)	inactiveness (noun)
	a disposition to remain inactive or inert
	the state of being inactive

inactive (adjective)	inactiveness (adjective)
(military) not involved in military operations
not active physically or mentally
(pathology) not progressing or increasing; or progressing slowly
lacking activity; lying idle or unused
lacking in energy or will
(of e.g. volcanoes) not erupting and not extinct
not exerting influence or change
not engaged in full-time work
not in physical motion
(chemistry) not participating in a chemical reaction; chemically inert