holy_of_holies
1. [ noun ] (religion) something that is regarded as inviolable or sacred
Examples:

"every politician fears to touch that holy of holies, the Social Security System"

Related terms: entity sacredness
2. [ noun ] (Judaism) sanctuary comprised of the innermost chamber of the Tabernacle in the Temple of Jerusalem where the Ark of the Covenant was kept
Synonyms: sanctum_sanctorum
Related terms: place_of_worship sanctuary Tabernacle Judaism