Knuckleball vs. Curveball — What's the Difference?

A knuckleball or knuckler is a baseball pitch thrown to minimize the spin of the ball in flight, causing an erratic, unpredictable motion. The air flow over a seam of the ball causes the ball to change from laminar to turbulent flow.

In baseball and softball, the curveball is a type of pitch thrown with a characteristic grip and hand movement that imparts forward spin to the ball, causing it to dive as it approaches the plate. Varieties of curveball include the 12–6 curveball, power curveball, and the knuckle curve.

A slow pitch that has almost no spin and veers erratically, thrown by gripping the ball with the nails or knuckles near the tips of the index and middle fingers, and often the third finger.

(Baseball) Any of several pitches that veer to the left when thrown with the right hand and to the right when thrown with the left hand.

(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.

(Slang) Something that is unexpected or designed to trick or deceive

(figurative) An event that is hard to predict.

(baseball) A forespin pitch thrown by rotating the index and middle fingers down and resulting in motion down "curve"

To pitch knuckleballs.

An unexpected turn of events initiated by an opponent or chance; an exception or outlier.

A baseball pitch thrown with little speed or spin

(baseball) To throw a curveball.