walk out vs walkout

walk out is not a noun while walkout is a noun.

Word	Noun	Adjective	Verb	Adverb
walk out	No	No	Yes	No
walkout	Yes	No	No	No

walk out (noun)	walkout (noun)
	a strike in which the workers walk out
	the act of walking out (of a meeting or organization) as a sign of protest

walk out (verb)	walkout (verb)
leave suddenly, often as an expression of disapproval
leave abruptly, often in protest or anger
stop work in order to press demands