Game concept
Religious Superior
The game also links it as Religious Superiors, Superior.
From the game's encyclopedia
A religious Superior is a Character who holds religious jurisdiction over one or more Subordinate religious clergy in a hierarchical religious structure.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Religious Superior is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A religious Superior is a Character who holds religious jurisdiction over one or more Subordinate religious clergy in a hierarchical religious structure." It is part of Religion. The game also links it as Religious Superiors and Superior. Patch 1.20.1.2, from game/common/game_concepts/pam_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/pam_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.