face-off vs face off

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

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