noun, someone that is extremely cheap at a computer game and uses tactics to kill other people that require no skill or knowledge to use. Often a noob will use those methods over and over and piss people off, while showing that he has no skill in his playing.
In Halo: Combat Evloved, someone using a fuel rod gun while sitting right behind your teleporter, who instantly kills you when you appear. the gun kills in 2 hits and you don't have to reload it. OR, someone who runs you over in a warthog because they don't know how to use a gun.