Definitions
1.nounAn offensive back whose primary job is to pass the ball in a play.
2.nounAn offensive back who receives the snap (hike) and then blocks the defense from crossing the line of scrimmage; a blocking back.
3.noun(rugby football) A position just behind the forwards, or one who plays this position.
4.verbTo play the position of quarterback.
5.verb(by extension) To lead a team or group; to be primarily responsible for some group project or activity.