hooter vs automobile horn

hooter and automobile horn both are nouns.

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

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

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

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

hooter (noun)	automobile horn (noun)
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
a device on an automobile for making a warning noise
informal terms for the nose