turn off vs turnoff

turn off is not a noun while turnoff is a noun.

Word	Noun	Adjective	Verb	Adverb
turn off	No	No	Yes	No
turnoff	Yes	No	No	No

turn off (noun)	turnoff (noun)
	a side road where you can turn off
	something causing antagonism or loss of interest

turn off (verb)	turnoff (verb)
cause to stop operating by disengaging a switch
cause to feel intense dislike or distaste
make a turn