make believe vs make-believe

make believe is not a noun while make-believe is a noun.

Word	Noun	Adjective	Verb	Adverb
make believe	No	No	Yes	No
make-believe	Yes	Yes	No	No

make believe (noun)	make-believe (noun)
	the enactment of a pretense
	imaginative intellectual play

make believe (adjective)	make-believe (adjective)
	imagined as in a play

make believe (verb)	make-believe (verb)
represent fictitiously, as in a play, or pretend to be or act like