karcero

Three words, and they are not the same word. Prizono is the prison as an institution, and malliberejo is the built Zamenhofan synonym for it that the older literature prefers. Ĉelo is a cell in the neutral sense: the room a prisoner is kept in, and equally a cell of the body or of a honeycomb. Karcero is narrower and darker than either. It is the small cell used for punishment - the dungeon under the kastelo, the black hole, the barrack lock-up a soldier is put in for a few days, the room the school kept for detention. A prizono is where you serve a sentence; a karcero is where you are shut for a while to be punished.

The German detour explains the odd second sense. In nineteenth-century German universities the Karzer was a lock-up on the premises, and students sent to it for duelling or for a night's noise decorated the walls; several of these rooms survive as museums in Heidelberg and Göttingen. Esperanto took the word in that era, which is why karcero covers both the medieval dungeon and the institutional detention room, and why it still carries a faint schoolroom sense alongside the grim one.

Register. This is a historical and literary word. Modern Esperanto writing about the criminal justice system uses prizono, malliberejo and ĉelo; karcero turns up in translated novels, in accounts of castles and monasteries, and in prison memoirs where the writer means solitary confinement specifically. Enkarcerigi is to lock somebody up in one, and karcerulo the person inside.