swab has 3 distinct synonyms spread across 3 of its 4 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.
implement consisting of a small piece of cotton that is used to apply medication or cleanse a wound or obtain a specimen of a secretion
cleaning implement consisting of absorbent material fastened to a handle; for cleaning floors
Synonyms, antonyms and the broader and narrower relations for swab come from Princeton University’s WordNet. Full sources and licences.