A person who tries to act like something to be cool. One who says they are one thing, usually goth/emo/gangsta/Hardcore etc. when they obviously aren't.Poseurs don't realize that they are being poseur half the time, which makes it worse. Oh, and skaters. Skaters, Goths, and Gangsta seem to be the most prevelent groups to have poseurs.
Yes, it is Poseur. Read the top rated post, it's explains it all.