foghorn vs signaling device

foghorn and signaling device both are nouns.

Word	Noun	Adjective	Verb	Adverb
foghorn	Yes	No	No	No
signaling device	Yes	No	No	No

As nouns, signaling device is a hypernym of foghorn; that is, signaling device is a word with a broader meaning than foghorn:

foghorn: a warning device consisting of a horn that generates a loud low tone
signaling device: a device used to send signals

Other hypernyms of foghorn include horn.

foghorn (noun)	signaling device (noun)
a warning device consisting of a horn that generates a loud low tone	a device used to send signals
a loud low warning signal that can be heard by fogbound ships