Game concept
Virtue
The game also links it as Virtues, Virtuous.
From the game's encyclopedia
Every Rite considers certain Traits to be Virtuous. Characters with these Traits gain Opinion bonuses from all characters who consider those traits Virtuous, even if they do not share the same Rite. In addition, Characters who have Traits that their own Rite considers Virtuous will gain bonus Piety every month.
Exactly what traits are considered to be Virtues varies from Rite to Rite, but is typically determined by a combination of that Rite's Tenets and the Religion the Rite belongs to.
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.
Virtue is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Every Rite considers certain Traits to be Virtuous." It covers Virtue Weight. The game also links it as Virtues and Virtuous. 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.