n00b is a derivitive of the word "noobie", which is a cooler way of saying "newbie". n00b's are people who aren't good at online gaming. Usually, people call others "n00b's" after they beat them in a game. A newb is someone who is new to a game, whether they're good or not. A noob doesn't necessarily mean someone who is new to the game, it is mostly referring to someone who isn't good at the game.
All the different ways of saying "Newbie" refer to gaming, if the ones who are speaking it are talking about gaming.
"Mrs. Torkos is a total n00b. She has no micro whatsoever."
"These definitions mean nothing, because any n00b can submit a definition and claim it to be real, not matter how inaccurate it is."