0 a horn that makes a very loud sound to warn ships that they are close to land or other ships:
He has a voice like a foghorn (= an unpleasantly loud voice).
1 a loud horn that a ship uses in a fog to warn other ships of its position
It is not purely psychological; it is not a foghorn, it is not a stunt.
The days of foghorn diplomacy—of shouting, but not being heard—are over.
The types of sounds recorded on this project included natural ambiences, signifiers such as bells, chimes and foghorns, as well as mechanical and industrial sounds.
A foghorn was also installed, with two quick blasts every five minutes.
Duke realizes that the foghorn came through the barn from a real foghorn near the barn, so he goes to find it in his charts.
The lighthouse included a launch ramp for a lifeboat, as well as an old naval carronade for firing blank charges as a crude foghorn.
A large foghorn alerted ships in fog and in bad visibility.
Now in areas of fog the lights are typically combined with a foghorn.