cover up vs cover-up

cover up is not a noun while cover-up is a noun.

Word	Noun	Adjective	Verb	Adverb
cover up	No	No	Yes	No
cover-up	Yes	No	No	No

cover up (noun)	cover-up (noun)
	concealment that attempts to prevent something scandalous from becoming public

cover up (verb)	cover-up (verb)
hide from view or knowledge