adjective
causing or deserving strong dislike or hatred; being so repugnant as to stir up positive antagonism
His abhorrent behavior at the festival led to a mob chasing him off and guards summoned to arrest him.
This word is used fairly commonly, but I think for GMs it’s nice to know that it’s an extreme form of repugnant. One can be repugnant and not inspire people to act, but abhorrent behavior, attitude, or condition is so bad someone will act.