The meaning of 'underground cell' is apparently from the 14th century: http://www.etymonline.com/index.php?term=dungeon http://www.etymonline.com/index.php?term

The meaning of 'underground cell' is apparently from the 14th century: http://www.etymonline.com/index.php?term=dungeon http://www.etymonline.com/index.php?term=dungeon