enter vs theater

enter is not a noun while theater is a noun.

Word	Noun	Adjective	Verb	Adverb
enter	No	No	Yes	No
theater	Yes	No	No	No

enter (noun)	theater (noun)
	a building where theatrical performances or motion-picture shows can be presented
	the art of writing and producing plays
	a region in which active military operations are in progress

enter (verb)	theater (verb)
set out on (an enterprise or subject of study)
make a record of; set down in permanent form
become a participant; be involved in
put or introduce into something
come on stage
to come or go into
take on duties or office
register formally as a participant or member
be or play a part of or in