Emery ball

Illegal baseball pitch

An emery ball is an illegal pitch in baseball, in which the ball has been altered by scuffing it with a rough surface, such as an emery board or sandpaper. This technique alters the spin of the ball, causing it to move in an atypical manner, as more spin makes the ball rise, while less spin makes the ball drop. The general term for altering the ball in any way is doctoring. The emery ball differs from the spitball, in which the ball is doctored by applying saliva or Vaseline. Vaseline or saliva smooths the baseball, while the emery paper roughens it.

This keyword could refer to multiple things. Here are some suggestions: