The Collaborative International Dictionary of English v.0.48:

quarterback \quarterback\ n. (Football)
   The player on a football tream who chooses the offensive play
   and receives the ball from the center at the start of each
   down. Compare halfback and fullback.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

quarterback \quarterback\ v. i. (Football)
   To play the position of quarterback, in a football game.

   Syn: play the quarterback, be the quarterback.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

quarterback
    n 1: (football) the person who plays quarterback [syn:
         quarterback, signal caller, field general]
    2: (American football) the position of the football player in
       the backfield who directs the offensive play of his team;
       "quarterback is the most important position on the team"
       [syn: quarterback, signal caller, field general]
    v 1: play the quarterback

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "quarterback":
   amateur athlete, archer, athlete, ballplayer, baseballer, baseman,
   batter, battery, be responsible for, blocking back, boss, bowman,
   call the signals, captain, carry on, catcher, center, chaperon,
   coach, command, competitor, conduct, control, cricketer,
   defensive lineman, direct, end, engineer, footballer, games-player,
   gamester, govern, guard, handle, head, head up, infielder, jock,
   jumper, lead, lead on, lineman, make the rules, manage, maneuver,
   manipulate, mastermind, offensive lineman, officer, order,
   outfield, outfielder, overlook, oversee, player, poloist,
   prescribe, professional athlete, pugilist, pull the strings, racer,
   regulate, run, skater, skipper, sport, sportsman, superintend,
   survey, tackle, tailback, take command, take the lead, toxophilite,
   wingback, wrestler