Etymology: Middle English holi of halowes, translation of Late Latin sanctum sanctorum, translation of Greek to hagion tōn hagiōn, translation of Hebrew qōdhesh haqqŏdhāshīm
1.
a. : the innermost chamber of a Jewish temple
b. : the bema in an Eastern Orthodox church : sanctuary
c. : a very sacred place
father's study was always considered the holy of holies by the children
2. : something considered as if very sacred
defeated that legislative holy of holies, a veterans' pension bill — Newsweek