automobile horn vs hooter

automobile horn and hooter both are nouns.

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

As nouns, automobile horn and hooter are synonyms defined as:

automobile horn and hooter: a device on an automobile for making a warning noise

Other synonyms of automobile horn include car horn, horn, motor horn.

automobile horn (noun)	hooter (noun)
a device on an automobile for making a warning noise	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes
	a device on an automobile for making a warning noise
	informal terms for the nose