inactivity vs inactive

inactivity is a noun but inactive is not a noun.

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

inactivity (noun)	inactive (noun)
being inactive; being less active
a disposition to remain inactive or inert
the state of being inactive

inactivity (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