A system of drains.
A downward wind.
A natural or artificial means for the removal of fluids from a given area by its draining away.
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.