eden has 6 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.
any place of complete bliss and delight and peace
a beautiful garden where Adam and Eve were placed at the Creation; when they disobeyed and ate the forbidden fruit from the tree of knowledge of good and evil they were driven from their paradise (the fall of man)
Synonyms, antonyms and the broader and narrower relations for eden come from Princeton University’s WordNet. Full sources and licences.