Source : Webster's Revised Unabridged Dictionary (1913)

Corner \Cor"ner\, n. (Association Football) [More fully {corner
   kick}.]
   A free kick from close to the nearest corner flag post,
   allowed to the opposite side when a player has sent the ball
   behind his own goal line.

Source : WordNet®

corner kick
     n : a free kick from the corner awarded to the other side when a
         player has sent the ball behind his own goal line