e has 8 distinct synonyms spread across 3 of its 5 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 fat-soluble vitamin that is essential for normal reproduction; an important antioxidant that neutralizes free radicals in the body
a radioactive transuranic element produced by bombarding plutonium with neutrons
the cardinal compass point that is at 90 degrees
the base of the natural system of logarithms; approximately equal to 2.718282...
Synonyms, antonyms and the broader and narrower relations for e come from Princeton University’s WordNet. Full sources and licences.