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