1The foot which is placed further back when a particular stance or posture is adopted, or when a particular action is performed. In later use often in the context of sport or dancing.
The foot closest to the wicket when the batsman stands at the crease. Especially in "off (also on) the back foot": with the batsman moving backwards before striking the ball; with the foot closest to the wicket bearing most of the weight of the batsman's body.
3British, Australian, New Zealand "on the back foot": (originally Boxing) in a defensive position or stance; (hence figurative) at a disadvantage; on the defensive. Often in "to put (also get, catch,etc.) (a person) on the back foot" and variants: to gain an advantage over (a competitor or opponent); to get the better of (a person or group).
4The lower part of one of the rear legs of a chair, table, or other object.
5Usually in plural. Any of the hind feet of an animal or other organism; especially either of the hind feet of a quadruped.
Designating a shot played from close to the wicket, with the foot closest to the wicket bearing most of the weight of the body.
Early 16th century; earliest use found in Gavin Douglas (c1476–1522), poet and bishop of Dunkeld. From back + foot.