Meaning of split-fingered fastball

split'-fin•gered fast'ball

Pronunciation: (split'fing"gurd), [key]
— Baseball. Baseball.
  1. a pitch, similar to the forkball but thrown with the same arm speed as a fastball, that drops suddenly as it nears the batter.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.