In (院) originally meant a large construction surrounded by high walls, but it also refers to the following:
The title of the Daijo Tenno (the Retired Emperor), the Cloistered Emperor, or the Nyo-in (Empress). Ingo (title of nobles). It originally meant the Gosho (Palace) of the Retired Emperor, Cloistered Emperor, or Nyo-in, but it developed to mean the person who lived there.
Names of government institutions.
Examples in Japan are as follows:
Jinji-in (National Personnel Authority)
Kaikei kensa-in (Board of Audit)
Genshiryoku anzen hoan-in (Nuclear and Industrial Safety Agency)
Kokudo chiri-in (Geographical Survey Institute)
Shugi-in (the House of Representatives) and Sangi-in (the House of Councillors)
Shonen-in (juvenile reformatory)
Names of educational institutions. Gaku-in (institute/academy), Daigaku-in (graduate school), and Gakushu-in (the Gakushu-in School Corporation).
Byoin (hospitals) and Iin (clinics). Sanin (maternity hospitals), Yoroin (homes for the elderly), and Seyaku-in (free hospitals for poor people).
Posthumous Buddhist name. Ingo: posthumous Buddhist name that includes "in."
Abbreviated names or derivative words related to government institutions, schools, hospitals, and clinics: Innai (inside a hospital), Taiin (discharge from hospital), Incho (hospital director), and Insei (graduate student).