cork has 6 distinct synonyms spread across 4 of its 7 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 one recorded opposite is uncork.
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.
outer bark of the cork oak; used for stoppers for bottles etc.
stuff with cork
“The baseball player stuffed his bat with cork to make it lighter”
Synonyms, antonyms and the broader and narrower relations for cork come from Princeton University’s WordNet. Full sources and licences.