Definitions for "Overstable"
Keywords:  backhand, thrown, throwing, disc, fade
A disc that, when thrown straight, will usually turn hard to the left for a right-handed player throwing backhand.
A disc which tends to turn or fade to the left for right-handed players using the backhand technique.
This means that a disc naturally will want to curve in the direction opposite of the person's throwing hand when thrown flat. Wind will also play an important factor in whether the disc would curve.