cistern

/ˈsɪstərn/

/ˈsɪstən/

Other forms: cisterns

A cistern is an underground tank that holds water. A long time ago, cistern water was used for drinking, but nowadays developed parts of the world mainly use it for watering plants and flushing toilets.

The oldest cisterns that we know of were built in the Middle East about 12,000 years ago, which is around when farming was invented. That's no coincidence. It would be tough to collect enough water to grow barley and wheat without storing the water in something, especially in a place as dry as the Middle East.

Definitions of cistern

1. noun

   a sac or cavity containing fluid especially lymph or cerebrospinal fluid
   synonyms: cisterna

   type of:

   sac

   a structure resembling a bag in an animal
2. noun

   an artificial reservoir for storing liquids; especially an underground tank for storing rainwater
   types:

   cesspit, cesspool, sink, sump

   a covered cistern; waste water and sewage flow into it

   rain barrel

   a barrel used as a cistern to hold rainwater

   type of:

   pool

   an excavation that is (usually) filled with water

   reservoir

   tank used for collecting and storing a liquid (as water or oil)
3. noun

   a tank that holds the water used to flush a toilet
   synonyms: water tank

   type of:

   storage tank, tank

   a large (usually metallic) vessel for holding gases or liquids