confined has 3 distinct synonyms spread across 1 of its 3 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 2 recorded opposites are invasive, unconfined.
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.
not invading healthy tissue
not free to move about
being in captivity
Synonyms, antonyms and the broader and narrower relations for confined come from Princeton University’s WordNet. Full sources and licences.