jet has 20 distinct synonyms spread across 7 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 hard black form of lignite that takes a brilliant polish and is used in jewelry or ornamentation
atmospheric discharges (lasting 10 msec) bursting from the tops of giant storm clouds in blue cones that widen as they flash upward
street names for ketamine
of the blackest black; similar to the color of jet or coal
Synonyms, antonyms and the broader and narrower relations for jet come from Princeton University’s WordNet. Full sources and licences.