Sunder is a fictional character, a mutant in the Marvel Universe. He was created by Chris Claremont and Paul Smith in Uncanny X-Men #169 (1983). Sunder was a member and founder of the Morlocks and the "Muir Island" X-Men.

To disunite in almost any manner, either by rending, cutting, or breaking; to part; to put or keep apart; to separate; to divide; to sever; as, to sunder a rope; to sunder a limb; to sunder friends.

break apart or in two, using violence

A warrior ability. Often used to draw aggro - and as a way to tell the other party/raid members when to attack the tank's target. I.e. "Wait until he has two sunders before attacking."

To expose to the sun and wind.

A separation into parts; a division or severance.