Faction

faction, n., v., EverQuest-ism 1. in general usage, a group, usu. contentious; from Middle French, from Latin faction-, factio (act of making, to fashion). 
2. on EverQuest and other MMORPGs, the rating of how well a certain group of NPCs like or dislike a character. [GJ1] 
3. the fifteen Sigilian political groups from AD&D 2nd Edition's spin-off Planescape. [QeR]
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Addendum (Def. #2): Whether you are able to enter a given town freely, or you are KoS by the town guard, depends largely on faction. A character's faction is changed by the completion of quests or the killing of different mobs. [GJ1]