sanctum
n. countable C1 Advanced US //ˈsæŋktəm// UK //sˈɑːnktəm// sanc·tum
n. a private, holy, or very special place. You use this word for a room or area that is kept secret or treated with great respect.
n. a sacred or private place, often one that is inaccessible to the public. Frequently used in the plural to describe the innermost parts of an organization or a person's private life.
The library was his private sanctum where he worked every day.
The CEO's office was a sanctum of silence, where no phone calls were ever answered.
The temple's inner sanctum was reserved for the high priests, who alone were permitted to perform the rituals required to maintain the city's spiritual balance.
From Latin sānctum (“that which is holy”).