plug in vs join

plug in is not a noun while join is a noun.

Word	Noun	Adjective	Verb	Adverb
plug in	No	No	Yes	No
join	Yes	No	Yes	No

plug in (noun)	join (noun)
	a set containing all and only the members of two or more given sets
	the shape or manner in which things come together and a connection is made

plug in (verb)	join (verb)
plug into an outlet	make contact or come together
	cause to become joined or linked
	become part of; become a member of a group or organization
	come into the company of
	be or become joined or united or linked