sink has 18 distinct synonyms spread across 10 of its 13 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. Its 2 recorded opposites are float, source.
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.
plumbing fixture consisting of a water basin fixed to a wall or floor and having a drainpipe
(technology) a process that acts to absorb or remove energy or a substance from a system
“the ocean is a sink for carbon dioxide”
Synonyms, antonyms and the broader and narrower relations for sink come from Princeton University’s WordNet. Full sources and licences.
a depression in the ground communicating with a subterranean passage (especially in limestone) and formed by solution or by collapse of a cavern roof