- (baseball) A 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.
- An event that is hard to predict.
- Our vendor keeps throwing us knuckleballs.
(third-person singular simple present knuckleballs, present participle knuckleballing, simple past and past participle knuckleballed)
- (intransitive, baseball) To pitch knuckleballs.