capsule has 10 distinct synonyms spread across 5 of its 9 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.
a pill in the form of a small rounded gelatinous container with medicine inside
a dry dehiscent seed vessel or the spore-containing structure of e.g. mosses
a structure that encloses a body part
a spacecraft designed to transport people and support human life in outer space
a pilot's seat in an airplane that can be forcibly ejected in the case of an emergency; then the pilot descends by parachute
put in a short or concise form; reduce in volume
“capsulize the news”
Synonyms, antonyms and the broader and narrower relations for capsule come from Princeton University’s WordNet. Full sources and licences.