Because I feel as though I’ve been living in one for the past week…

oubliette (ou·bli·ette): / oo blee ET /
noun

(1) a dungeon or underground cell, especially one that is secret or hidden and perfectly dark, with a trapdoor at the top that is the only way in or out

[From French oubliette from Middle French oublier meaning “to forget,” from Old French oblier from Vulgar Latin oblitare, derivative of Latin oblitus, past participle (frequentative) of Latin oblivisci meaning “to forget.”]

Usage: Prisoners held in an oubliette often were subjected to perpetual confinement in absolute darkness, hence the dungeon’s moniker as a place where one would be forgotten, or more specifically, the “place of forgetfulness.”