pool has 6 distinct synonyms spread across 6 of its 11 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
an excavation that is (usually) filled with water
a small lake
“the pond was too small for sailing”
Synonyms, antonyms and the broader and narrower relations for pool come from Princeton University’s WordNet. Full sources and licences.
an organization of people or resources that can be shared
“a car pool”
an association of companies for some definite purpose
any communal combination of funds
“everyone contributed to the pool”
a small body of standing water (rainwater) or other liquid
“there were puddles of muddy water in the road after the rain”
something resembling a pool of liquid
“he stood in a pool of light”
any of various games played on a pool table having 6 pockets