#back.football_player  (football) a person who plays in the backfield
  supertype:  #football_player__footballer  an athlete who plays American football
  subtype:  #flankerback__flanker  a back stationed wide of the scrimmage line; used as a pass receiver
  subtype:  #signal_caller__quarterback__field_general__fieldgeneral  (football) the person who plays quarterback
  subtype:  #running_back__runningback  (football) a back on the offensive team (a fullback or halfback) who tries to advance the ball by carrying it on plays from the line of scrimmage
     subtype:  #fullback.running_back  (football) the running back who plays the fullback position on the offensive team
     subtype:  #halfback.running_back  (football) the running back who plays the offensive halfback position
  subtype:  #tailback.back  (football) the person who plays tailback
  subtype:  #wingback.back  (football) the person who plays wingback

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