A defender charged with covering the opposing team's wide receiver. There are usually two cornerbacks â€“ one on each side of the field. Usually the noisiest players on a team, the only thing that moves faster than a cornerback's feet is his mouth.
A cornerback (also referred to as a corner) is a position in American and Canadian football, more broadly classified as a defensive back. Widely accepted as being the most difficult of all the positions, the modern cornerback is ideally very fast, agile, and has good football instincts. Like any defensive player, he must be able to react faster than his opponent, since he does not have the luxury of knowing where a play is going to go.