In American football, a nickelback is a cornerback or safety who serves as the additional defensive back in a nickel defense. A base defense consists of two cornerbacks and two safeties, making the nickelback the fifth defensive back on the field, thus tying the name of the position to the name of the North American 5-cent piece. In Canadian football or CFL, where five defensive backs are considered the norm, the position is known as a defensive halfback. * v * t * e