To flow in the wrong or backward direction.
The flow of a fluid (through a pipe etc.) in a direction opposite to that which is normal or intended.
To flow outward.
Any outward movement.
Something that flows out of a sewage treatment plant.
The process of flowing out.
A fluid that flows out.
A stream of gaseous material emanating from an active galactic nucleus.
The part of a system that allows material to flow out.