Game concept
Regency
The game also links it as Regencies, Regency's, Regencies'.
From the game's encyclopedia
A Regency is a special form of Power Sharing for when the Ruler is not able to rule their Realm on their own.
It generally occurs if the Ruler is a Child, Imprisoned, Incapable, or attending an Activity outside their Realm.
A Regency that persists too long may become an Entrenched Regency.
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.
Regency is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A Regency is a special form of Power Sharing for when the Ruler is not able to rule their Realm on their own." It is part of Power Sharing. It covers Regent, Diarchy Veto, Regency Succession Score, Entrenched Regency and Mandate. The game also links it as Regencies, Regency's and Regencies'. Patch 1.20.1.2, from game/common/game_concepts/04_ep2_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/04_ep2_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.