Isn't Noob a word for someone who just acts like he doesn't know what he's going? You know, that guy who joins your TDM and messes up all of Whatever Team's plans, then when he gets in trouble, he'll just say "Oh no, I'm new, so I don't know how to do this"
EDIT: And someone who actually is new to a game is called a Newb, or Newbie to avoid confusion with the word Noob, which is commonly if not always used as an insult.