A pinch is a grip of a flexible object in which a portion is taken between two fingers, until it hurts, or something of resemblance and squeezed so the gripped portion of the object is lifted from its normal level. By extension, that which is taken in the grip is referred to as a "pinch."
When the fingers are used to perform a pinch, the action usually consists of the thumb and one other finger. The closer to the thumb the other finger is located, the stronger the pinch.