Game concept
Leasing
The game also links it as Lease, Leases, Leased, Lessee.
From the game's encyclopedia
Minor Baronies can be leased out to Holy Orders, Monastic Orders, or Clergy. Leased baronies provide Taxes and Levies to the Lessee rather than the Holder.
Military Orders can lease Castle Holdings and City Holdings, while Monastic Orders and clergy can lease Temple Holdings. A lease may have a Lease Contract.
Leased Holdings are still considered part of the holder's Realm. County Capitals cannot be leased.
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.
Leasing is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Minor Baronies can be leased out to Holy Orders, Monastic Orders, or Clergy." The game also links it as Lease, Leases, Leased and Lessee. 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.