institutionalized has 1 distinct synonym 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 noninstitutionalized.
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.
officially placed in or committed to a specialized institution
“had hopes of rehabilitating the institutionalized juvenile delinquents”
given the character of an institution or incorporated into a structured and usually well-established system
“institutionalized graft”
Synonyms, antonyms and the broader and narrower relations for institutionalized come from Princeton University’s WordNet. Full sources and licences.