impotence has 2 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. Its one recorded opposite is potence.
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.
the quality of lacking strength or power; being weak and feeble
an inability (usually of the male animal) to copulate
Synonyms, antonyms and the broader and narrower relations for impotence come from Princeton University’s WordNet. Full sources and licences.