Definition

1. Purposefully shooting or otherwise sabotaging your teammates in an online game.

2. In online gaming where one repeatedly killing the same individual or individuals over and over again, or camping their corpse to prevent them from retrieving it, or otherwise performing actions in a game to prevent the player from enjoying the game.

3. In online gaming, someone who takes pleasure in creating grief for an opponent via various "cheap" tactics.

• For example: I wish Jork would stop friggen griefing my guild mates everytime we log in and play.

Taken from: http://www.urbandictionary.com/define.php?term=griefing