cistern

English Thesaurus

1. an artificial reservoir for storing liquids; especially an underground tank for storing rainwater (noun.artifact)

hypernym	:	pool,
definition	:	an excavation that is (usually) filled with water (noun.artifact)

hypernym	:	reservoir,
definition	:	tank used for collecting and storing a liquid (as water or oil) (noun.artifact)

hyponym	:	cesspit, cesspool, sink, sump,
definition	:	a covered cistern; waste water and sewage flow into it (noun.artifact)

hyponym	:	rain barrel,
definition	:	a barrel used as a cistern to hold rainwater (noun.artifact)

2. a tank that holds the water used to flush a toilet (noun.artifact)

hypernym	:	storage tank, tank,
definition	:	a large (usually metallic) vessel for holding gases or liquids (noun.artifact)

3. a sac or cavity containing fluid especially lymph or cerebrospinal fluid (noun.body)

hypernym	:	sac,
definition	:	a structure resembling a bag in an animal (noun.body)