superhuman has no recorded synonym. 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 subhuman.
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.
above or beyond the human or demanding more than human power or endurance
“superhuman beings”
Synonyms, antonyms and the broader and narrower relations for superhuman come from Princeton University’s WordNet. Full sources and licences.