Drain can refer to:

• A tube used to drain pus or other fluids from a wound. See Drain (surgery)
• agriculture, see drainage
• A exit-point for soiled water in a plumbing system (e.g., on the floor of a room, or at the bottom of a tub).
• A system of collecting and disposing of rainwater in an urban area. See Storm drain.
• Drain , a commune in the Maine-et-Loire département in France
• A colloquial term for the Underground's Waterloo_&_City_Line in London