A slow pitch which moves erratically, made by releasing the ball from the knuckles of the first joints of the index and middle finger.
- ‘You'll learn the rules of offense and defense, and all about fastballs, curveballs, knuckleballs and screwballs.’
- ‘He had pitched in high school and occasionally had thrown a knuckleball.’
- ‘Wilhelm and Niekro are the only two pitchers in the Hall of Fame who relied primarily on the knuckleball throughout their careers.’
- ‘Eddie Cicotte is thought to be the first major league pitcher to specialize in throwing the knuckleball.’
- ‘Sauveur throws a fastball, knuckleball, curveball and cutter, and he changes speeds with all of them.’