cistern

noun

1. A reservoir or tank for holding water, especially for catching and holding rainwater for later use.

   “1913, A.C. Cotter, Catholic Encyclopedia, "Wells in Scripture", Their extreme necessity is attested by the countless number of old, unused cisterns with which the Holy Land is literally honeycombed.”

   “On a broad ledge near the top, we found a stone cabin. Higher up was a cistern and a few more terraces.”

   “Cisterns (bôr, bō'r), mentioned frequently in the Bible, are artificial reservoirs, usually cut into bedrock, for collecting and conserving rain runoff from roofs and courtyards.”

2. In a flush toilet, the container in which the water used for flushing is held; a toilet tank.

   “It is possible to connect your tank to your toilet cistern and/or garden, so that even if the water is not drinkable it still can be used productively to make major water savings.”

3. A shallow, typically oval, vessel made of porcelain, pottery, or glass.
4. The receptacle that holds the fuel in an oil lamp.

   “By next winter he was spending every evening poring over the work of Théodore Agrippa d'Aubigné on the French Reformation by the light of a little oil lamp, with a tiny cistern the size of an orange and no chimney[.]”

5. A cisterna.
6. The vessel surrounding the condenser in a steam engine.