Blowhole

Part of speech: noun (n.)

1. A cavern in a cliff, at the water level, opening to the air at its farther extremity, so that the waters rush in with each surge and rise in a lofty jet from the extremity.

2. A nostril or spiracle in the top of the head of a whale or other cetacean.

3. A hole in the ice to which whales, seals, etc., come to breathe.

4. An air hole in a casting.