elliptical has 8 distinct synonyms spread across 2 of its 2 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.
rounded like an egg
characterized by extreme economy of expression or omission of superfluous elements
“the dialogue is elliptic and full of dark hints”
Synonyms, antonyms and the broader and narrower relations for elliptical come from Princeton University’s WordNet. Full sources and licences.