Game concept
Unlanded
From the game's encyclopedia
Unlanded Characters have no Holdings in their Domain, but can theoretically still be Rulers of a sort. For example, this can be the case for Heads of Faith and the Grand Masters of Holy Orders.
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.
Unlanded is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Unlanded Characters have no Holdings in their Domain, but can theoretically still be Rulers of a sort." Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.