This page provides all possible meanings and translations of the word oubliette
a dungeon with the only entrance or exit being a trap door in the ceiling
A dungeon only accessible by a trapdoor at the top.
Origin: From oubliette, from oublier.
The Nuttall Encyclopedia
an underground cell, perfectly dark, in which prisoners were subjected to perpetual confinement, was so called as being a "place of forgetfulness," or where one is forgotten; they were often put secretly to death.