Breaker

1. A shallow portion of a reef over which waves break.
2. A breaking wave that breaks into foam against the shore, a shoal, a rock or a reef. Sailors use breakers to warn themselves of their vessel's proximity to an underwater hazard to navigation or, at night or during periods of poor visibility, of their vessel's proximity to shore.
3. A ship breaker, often used in the plural, e.g. "The old ship went to the breakers".
4. A small cask of liquid kept permanently in a ship's boat in case of becoming separated from the ship or if used as a lifeboat.