v. to sound loudly; -- of car horns.
Syn. -- honk, blare, beep, toot, klaxon. [ WordNet 1.5 ]

2. to use the horn of a car.
Syn. -- honk. [ WordNet 1.5 ]

n. a kind of loud horn formerly used on motor vehicles.
Syn. -- klaxon. [ WordNet 1.5 ]