Cistern

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

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

artificial lake, bayou lake, dam, dead water, dike, etang, farm pond, fishpond, freshwater lake, glacial lake, inland sea, lagoon, laguna, lake, lakelet, landlocked water, linn, loch, lough, mere, millpond, millpool, nyanza, oxbow lake, plash, pond, pondlet, pool, puddle, reservoir, salina, salt pond, stagnant water, standing water, still water, sump, tank, tarn, tidal pond, volcanic lake, water hole, water pocket, well