A gamer is someone who plays games. Nothing more, nothing less. Anything else in the definition is merely the individuals personal feelings on the subject.
What defines a gamer is the passion and love for video games. Gamers have more knowledge of a game and have more hype over non-gamers. Gamers are people reading this article who look up and read articles about a game and look for pics and vids. Gamers thirst for knowledge of a game and we usually have the ability to adapt to new games quickly. Gamers actually can figure certain problems in school faster than others. Gamers have to start playing games at a fairly early age.
This question was asked on the wiki: Wikia Gaming.