standby vs secondary

standby and secondary both are nouns.

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

standby (noun)	secondary (noun)
something that can be relied on when needed	coil such that current is induced in it by passing a current through the primary coil
an actor able to replace a regular performer when required	the defensive football players who line up behind the linemen

standby (adjective)	secondary (adjective)
ready for emergency use	being of second rank or importance or value; not direct or immediate
	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