1.NounA pitch thrown with the ball gripped on the fingertips and released with no rotation, which travels over an unpredictable path to the plate due to micro-turbulence in the air.
"Even the pitcher doesn't know where his knuckleball is going.; Boston Red Sox pitcher Tim Wakefield is best known for his use of the knuckleball."
2.NounA type of delivery where a fast bowler holds the ball on the knuckles of the index and middle fingers.