Medieval term for a keep.
The French word for the Keep tower. Not a dungeon in the sense we know. Most castles had a miserable little place that was used as a prison, but they were for the most part punishment pits for one or two recalcitrants. After castles had lost their original purpose in the 17th Century, quite a few gatehouses were converted into prisons (why gatehouses, I'm not too sure).
The principal tower of a castle; keep.
Inner stronghold or keep of the castle
French, for keep. The last and most formidable place of defense in a castle, usually set atop the motte, or some natural feature of limited accessibility. In this period it was nearly always constructed of wood.
Central stone keep of a medieval castle.
Donjon Original name for the keep or main tower. Prisoners were often kept in the lowest part - hence Dungeon.
Donjon is an independently published role-playing game by Clinton R. Nixon, published by Anvilwerks. It's a fantasy game that's both a parody of and an homage to Dungeons & Dragons.