A
player, typically in a multiplayer videogame, who does not play to win, but to cause as much greif and frustration foe the other players as possible,
even to the detriment of their own success in the
game.
God, that
guy is such a greifer. He just sits at the finish
line and rams everyone out of the way before they can pass him. He's not
even participating in the race, he's still on lap one.