Game concept
Adventurer
The game also links it as Adventurers, Adventurer's, Adventurers'.
From the game's encyclopedia
An Adventurer is an Unlanded Character who leads a Camp.
They do not have Vassals, nor do they earn income passively in the usual fashion — instead, they must take Contracts to earn their coin, or call in favors from their Roll of Patrons.
Adventurers may freely roam the map. Their main concern is making sure they have enough Provisions to survive on the move.
Instead of Crown Authority, most Adventurers will set a Camp Purpose. This indicates what type of group they have and why they stick together.
Driven seventh sons with no inheritance, ambitious nomads, petulant run-aways, curious scholars, vicious sell-swords, and deposed nobles alike all flesh out the ranks of these tireless wanderers.
Their sole uniting factor is a hunger for something more than a quiet life of obscurity, and the will to do something about it.
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.
Adventurer is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "An Adventurer is an Unlanded Character who leads a Camp." It covers Roll of Patrons and Camp Purpose. The game also links it as Adventurers, Adventurer's and Adventurers'. Patch 1.20.1.2, from game/common/game_concepts/07_ep3_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/07_ep3_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.