n. - A draining; a gradual flowing off of any liquid; also, that which flows out of a drain.
n. - The mode in which the waters of a country pass off by its streams and rivers.
n. - The system of drains and their operation, by which superfluous water is removed from towns, railway beds, mines, and other works.
n. - Area or district drained; as, the drainage of the Po, the Thames, etc.
n. - The act, process, or means of drawing off the pus or fluids from a wound, abscess, etc.