spiracle

A respiratory aperture, especially.

Any of several tracheal openings in the exoskeleton of an insect, spider, or other terrestrial arthropod.

A small respiratory opening behind the eye of most sharks and rays and certain other fishes.

The blowhole of a cetacean.

An aperture or opening through which air is admitted and expelled.

A vent for small explosive outbreaks, produced upon the surface of a still highly heated and at least partially molten lava-stream by the escape of imprisoned vapors. A little cone of ejected clots may gather around it.

An aperture or orifice.

In zoology, an aperture, orifice, or vent through which air, vapor, or water passes in the act of respiration; a breathing-hole; a spiraculum: applied to many different formations.

The nostril, or one of the nostrils, of whales, porpoises, and allied animals.