dungeon
Definitions
A strong, dark cell or underground chamber, typically located in a castle, used for confining prisoners.
A dark, subterranean room or series of passages, often depicted in fantasy literature and games as a place containing monsters or treasure.
Examples
The knight descended into the dark, damp dungeon to rescue the captive.
Ancient legends claim that a dragon guards a hoard of gold deep within the castle dungeon.
The prisoner spent many long years locked away in the cold stone dungeon.