automobile vs roof

automobile and roof both are nouns.

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

automobile (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
	protective covering on top of a motor vehicle
	an upper limit on what is allowed
	the inner top surface of a covered area or hollow space

automobile (verb)	roof (verb)
travel in an automobile	provide a building with a roof; cover a building with a roof