What is "peyrepertuse"

Peyrepertuse is a ruined fortress and one of the so-called Cathar castles located high in the French Pyrénées in the commune of Duilhac-sous-Peyrepertuse, in the Aude département, and has been associated with the Counts of Narbonne and Barcelona. It was the former seigneury of the Peyrepertusès (in Occitan : Pèirapertusés) which means "pierced stone."