face off vs face-off

face off is not a noun while face-off is a noun.

Word	Noun	Adjective	Verb	Adverb
face off	No	No	Yes	No
face-off	Yes	No	No	No

face off (noun)	face-off (noun)
	(ice hockey) the method of starting play; a referee drops the puck between two opposing players
	a hostile disagreement face-to-face

face off (verb)	face-off (verb)
start a game by a face-off