A knuckleball is a baseball pitch that is thrown with little to no spin, causing it to flutter erratically on its way to the plate. This makes it a very difficult pitch to hit, as batters cannot predict its movement.
Knuckleballs are thrown by gripping the ball with the knuckles of the index and middle fingers, and releasing it with a slight flick of the wrist. The lack of spin causes the ball to wobble and dart, making it very difficult for batters to square up.