What is the meaning of Cistern?

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

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

A shallow, typically oval, vessel made of porcelain, pottery, or glass.

The receptacle that holds the fuel in an oil lamp.

A cisterna.

The vessel surrounding the condenser in a steam engine.

cistern, tank

Source: wiktionary.org