cistern

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A receptacle for holding water or other liquid, especially a tank for catching and storing rainwater.
2. n. Anatomy A cisterna.

Century Dictionary and Cyclopedia

1. n. A natural or artificial receptacle or reservoir for holding or storing water or other fluid, most commonly consisting of mason-work sunk in the ground, but sometimes constructed of wood and placed on the tops of houses.
2. n. A vessel made of lead to hold a stock of water for household uses; also, one made of silver, copper, or other metal, to put bottles or glasses in.
3. n. The vessel inclosing the condenser of a condensing steamengine, and containing the injection-water.
4. n. The receptacle into which glass is ladled from the pots to be poured on the table in making plate-glass, or in casting glass; a cuvette.
5. n. In decorative art: A large vessel, generally of pottery or porcelain, shallow in proportion to its length and breadth, and usually oval in plan.
6. n. A tank or receptacle for water, usually hung upon the wall, and serving to give water, by a spigot or tap, for use in washing, etc.: often of faience or of copper, and a very decorative object. Compare fountain in this sense.
7. n. In anatomy, a reservoir or receptacle of some natural fluid of the body.
8. n. In mining, a tank in a deep shaft, serving an upper pump with water from a lower one.

Wiktionary

1. n. A reservoir or tank for holding water, especially for catching and holding rainwater for later use.
2. n. technical In a flush toilet, the container in which the water used for flushing is held; a toilet tank.
3. n. anatomy A cisterna.

GNU Webster's 1913

1. n. An artificial reservoir or tank for holding water, beer, or other liquids.
2. n. A natural reservoir; a hollow place containing water.

WordNet 3.0

1. n. an artificial reservoir for storing liquids; especially an underground tank for storing rainwater
2. n. a tank that holds the water used to flush a toilet
3. n. a sac or cavity containing fluid especially lymph or cerebrospinal fluid