nose dive vs nosedive

nose dive and nosedive both are nouns.

Word	Noun	Adjective	Verb	Adverb
nose dive	Yes	No	No	No
nosedive	Yes	No	Yes	No

As nouns, nose dive and nosedive are synonyms defined as:

Other synonyms of nose dive include dive.

nose dive (noun)	nosedive (noun)
a steep nose-down descent by an aircraft	a steep nose-down descent by an aircraft
	a sudden sharp drop or rapid decline

nose dive (verb)	nosedive (verb)
	plunge nose first; drop with the nose or front first, of aircraft