Definitions for backspinˈbækˌspɪn
Random House Webster's College Dictionary
reverse rotation of a ball causing it to bounce or roll backward or stop short.
Origin of backspin:
spin (usually of a moving ball) that retards or reverses the forward motion
Spin applied to a ball in order to slow it, change its flight, or stop it when it lands.
To spin (a ball) with this motion.