致仕

致 here means 'to return / hand back' (as in 致谢 'offer thanks'); 仕 means 'official career / post'. Codified by Confucian ritual as occurring at age 70 (《礼记》七十而致政), it became the standard term for civil-service retirement throughout imperial China - appearing constantly in dynastic histories.

Pure literary / classical Chinese. Modern speech uses 退休. Encounter 致仕 in historical texts, biographies of ancient officials, and the occasional newspaper column on tradition.