secondary vs unessential

secondary is a noun but unessential is not a noun.

Word	Noun	Adjective	Verb	Adverb
secondary	Yes	Yes	No	No
unessential	No	Yes	No	No

secondary (noun)	unessential (noun)
coil such that current is induced in it by passing a current through the primary coil
the defensive football players who line up behind the linemen

secondary (adjective)	unessential (adjective)
being of second rank or importance or value; not direct or immediate	not basic or fundamental
depending on or incidental to what is original or primary
inferior in rank or status
not of major importance
belonging to a lower class or rank