quarterback

Short definition from Wiktionary

Noun

1. 1
   An offensive back whose primary job is to pass the ball in a play.
2. 2
   An offensive back who receives the snap (hike) and then blocks the defense from crossing the line of scrimmage; a blocking back.
3. 3
   A position just behind the forwards, or one who plays this position.

Verb

1. 1
   To play the position of quarterback.
2. 2
   To lead a team or group; to be primarily responsible for some group project or activity.