Game concept · Advanced Activities
Contest
The game also links it as Contests.
From the game's encyclopedia
A Grand Tournament is comprised of a series of Contests, selected by the Activity Host, where Qualifying Contestants can compete to win Prizes and other rewards.
Each Contest uses one of four different ways to determine a winner: Knock-Out, Turns, Teams, and Race.
Your chance of winning a Contest is determined by your Skills, Traits, preparation, and other factors. Eligibility to enter physical Contests is determined by health and sex, based on the Culture and Faith of the Activity Host.
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.
Contest is an entry of Crusader Kings III's in-game encyclopedia (Advanced Activities). The game explains it: "A Grand Tournament is comprised of a series of Contests, selected by the Activity Host, where Qualifying Contestants can compete to win Prizes and other rewards." It is part of Grand Activity. The game also links it as Contests. 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.