reverse gear vs car

reverse gear and car both are nouns.

Word	Noun	Adjective	Verb	Adverb
reverse gear	Yes	No	No	No
car	Yes	No	No	No

reverse gear (noun)	car (noun)
the gears by which the motion of a machine can be reversed	a motor vehicle with four wheels; usually propelled by an internal combustion engine
	a wheeled vehicle adapted to the rails of railroad
	where passengers ride up and down
	the compartment that is suspended from an airship and that carries personnel and the cargo and the power plant
	a conveyance for passengers or freight on a cable railway