noob
Someone who is either new or terrible at a videogame. 

Noob is a variation on the word "newb" which is short for "newbie" which means "new at something"

The word "noob," however may refer to a player who has been playing a game for a very long time and is just especially unskilled at the game, or is extremely ignorant of the game's rules, lingo, customs, etc. In certain roleplaying games, a high level noob may sometimes be called a "froob" for reasons unknown to most. But usually only noobs call noobs froobs. 

See Also: Newb, Froob, Newbie, and Lowbie
"That noob doesn't know where Stormwind City is."

"You only got 10 kills? NOOB!"

"I am sick of noobs trying to sell me useless crap."