inactiveness vs inactive

inactiveness is a noun but inactive is not a noun.

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

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

inactiveness (adjective)	inactive (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