KS meaning and pronunciation
Shortened version of "Kill Steal"; A term used on MMORPGs to describe the act of barging in to kill a monster (or other enemy) that another player had been fighting first and receiving the XP that rightfully belonged to the first player to engage the enemy in battle. KSer: one who KSes; KSing: The act of commiting a KS.
KS definition by Urban Dictionary
KS definition by Urban Dictionary