theater vs appear

theater is a noun but appear is not a noun.

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

theater (noun)	appear (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

theater (verb)	appear (verb)
	come into sight or view
	be issued or published
	come into being or existence, or appear on the scene
	appear as a character on stage or appear in a play, etc.
	give a certain impression of being something or having a certain aspect
	(of a proposition) seem to be true, probable, or apparent
	present oneself formally, as before a (judicial) authority