The Collaborative International Dictionary of English v.0.48:
Drain \Drain\, n.
1. The act of draining, or of drawing off; gradual and
continuous outflow or withdrawal; as, the drain of specie
from a country; the project is a drain on resources.
2. That means of which anything is drained; a channel; a
trench; a water course; a sewer; a sink.
3. pl. The grain from the mashing tub; as, brewers' drains.
Box drain, Counter drain. See under Box, Counter.
Right of drain (Law), an easement or servitude by which one
man has a right to convey water in pipes through or over
the estate of another. --Kent.