hell has 15 distinct synonyms spread across 5 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. Its one recorded opposite is Heaven.
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.
(Christianity) the abode of Satan and the forces of evil; where sinners suffer eternal punishment
“Hurl'd headlong...To bottomless perdition, there to dwell”
(religion) the world of the dead
“No one goes to Hades with all his immense wealth”
Synonyms, antonyms and the broader and narrower relations for hell come from Princeton University’s WordNet. Full sources and licences.