unengaged vs idle

unengaged is not a noun while idle is a noun.

Word	Noun	Adjective	Verb	Adverb
unengaged	No	Yes	No	No
idle	Yes	Yes	Yes	No

unengaged (noun)	idle (noun)
	the state of an engine or other mechanism that is idling

unengaged (adjective)	idle (adjective)
not busy or occupied; free	not in action or at work
not promised in marriage	silly or trivial
	not in active use
	lacking a sense of restraint or responsibility
	not having a job
	not yielding a return
	without a basis in reason or fact

unengaged (verb)	idle (verb)
	run disconnected or idle
	be idle; exist in a changeless situation