A vent for the escape of steam or other 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.
The spiracle, on the top of the head, through which cetaceans breathe.
A vertical opening in the top of a computer case that lets hot air (primarily from the CPU heat sink) escape quickly.
An unintended cavity filled with air in a casting product.
To fill or be filled with air in an unintended cavity.
A fluid that flows out.
Any outward movement.
Something that flows out of a sewage treatment plant.
The process of flowing out.
A stream of gaseous material emanating from an active galactic nucleus.
The part of a system that allows material to flow out.
To flow outward.