This is about European castles. For other uses see Dungeon .]]A dungeon is a place where prisoners are kept. In the past, it used to double as the keep.EtymologyThe word dungeon was derived from the Old French donjon, which came from the Latin dominus, "lord".However, in French the term donjon means "keep" (a form of tower), and the term oubliette or cachot (a form of prison) is a more appropriate translation of the English "dungeon". This word is a false friend.History, Chris