sanctum sanctorum in WordNet English dictionary

1. (Judaism) sanctuary comprised of the innermost chamber of the Tabernacle in the temple of Solomon where the Ark of the Covenant was kept
   holy of holies  sanctum sanctorum 
   
2. a place of inviolable privacy
   "he withdrew to his sanctum sanctorum, where the children could never go"
   sanctum  sanctum sanctorum 
   

sanctum sanctorum in English Wiktionary