A facility for the correction and education of juvenile delinquents. This term is somewhat dated; modern usage often prefers 少年院 (shounen'in) for juvenile correctional facilities.
He was in a reformatory when he was young.
reform school; juvenile reformatory
Compound of 感化 (kanka, 'reform, influence') and 院 (in, 'institution'). The exact historical derivation is uncertain, but the term was used in the early 20th century for juvenile reform institutions.