Cauldron and Cistern

Cauldron noun - A very large pot that is used for boiling.

Cistern and cauldron are semantically related. in container topic. In some cases you can use "Cistern" instead a noun "Cauldron", when it comes to topics like holder for physical object, large container for liquids.

Cistern noun - A sac or cavity containing fluid especially lymph or cerebrospinal fluid.

Cauldron and cistern are semantically related. Sometimes you can use "Cauldron" instead a noun "Cistern".