car vs roof

car and roof both are nouns.

Word	Noun	Adjective	Verb	Adverb
car	Yes	No	No	No
roof	Yes	No	Yes	No

car (noun)	roof (noun)
a motor vehicle with four wheels; usually propelled by an internal combustion engine	a protective covering that covers or forms the top of a building
a wheeled vehicle adapted to the rails of railroad	protective covering on top of a motor vehicle
where passengers ride up and down	an upper limit on what is allowed
the compartment that is suspended from an airship and that carries personnel and the cargo and the power plant	the inner top surface of a covered area or hollow space
a conveyance for passengers or freight on a cable railway

car (verb)	roof (verb)
	provide a building with a roof; cover a building with a roof