make-believe vs make believe

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

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