car vs automobile horn

car and automobile horn both are nouns.

Word	Noun	Adjective	Verb	Adverb
car	Yes	No	No	No
automobile horn	Yes	No	No	No

car (noun)	automobile horn (noun)
a motor vehicle with four wheels; usually propelled by an internal combustion engine	a device on an automobile for making a warning noise
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