cube has 5 distinct synonyms spread across 5 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. 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 hexahedron with six equal squares as faces
a three-dimensional shape with six square or rectangular sides
Synonyms, antonyms and the broader and narrower relations for cube come from Princeton University’s WordNet. Full sources and licences.
any of several tropical American woody plants of the genus Lonchocarpus whose roots are used locally as a fish poison and commercially as a source of rotenone
a block in the (approximate) shape of a cube