bell buoy

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Nautical A buoy fitted with a warning bell that is activated by the movement of the waves.

Century Dictionary and Cyclopedia

1. n. See buoy.

Wiktionary

1. n. A buoy on which is mounted a bell with four clappers, hung inside an iron cage, which is rung by the motion of the waves

GNU Webster's 1913

1. n. a large buoy on which a bell is mounted, to be rung by the motion of the waves.

WordNet 3.0

1. n. a buoy with a bell on it