WordNet (r) 3.0 (2006):

signal caller
    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]