BLOWHOLE

vent, venthole, vent-hole, blowhole

(noun) a hole for the escape of gas or air

blowhole

(noun) the spiracle of a cetacean located far back on the skull

Source: WordNet® 3.1

Etymology

Noun

blowhole (plural blowholes)

The spiracle, on the top of the head, through which cetaceans breathe.

A vent for the escape of gas.

A top-facing opening to a cavity in the ground very near an ocean's shore, leading to a marine cave from which wave water or bursts of air are expelled.

(metallurgy) An unintended cavity filled with air in a casting product.

(computer hardware) A vertical opening in the top of computer cases, that let hot air, primarily from the CPU heat sink, escape quickly.

Verb

blowhole (third-person singular simple present blowholes, present participle blowholing, simple past and past participle blowholed)

(metallurgy, ambitransitive) To fill or be filled with air in an unintended cavity.

Source: Wiktionary

Blow"hole`, 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.

Note: There are two spiracles or blowholes in the common whales, but only one in sperm whales, porpoises, etc.

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

4. (Founding)

Definition: An air hole in a casting.

Source: Webster’s Unabridged Dictionary 1913 Edition