third gear vs car

third gear and car both are nouns.

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

third gear (noun)	car (noun)
the third from the lowest forward ratio gear in the gear box of a motor vehicle	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