Finger (unit)
A finger (sometimes fingerbreadth or finger's breadth) is any of several units of measurement that are approximately the width of an adult human finger, including: The digit, also known as digitus or digitus transversus (Latin), dactyl (Greek) or dactylus, or finger's breadth — of an inch or of a foot. In medicine and related disciplines (anatomy, radiology, etc.) the fingerbreadth (literally the width of a finger) is an informal but widely used unit of measure. In the measurement of distilled spirits, a finger of whiskey refers to the amount of whiskey that would fill a glass to  the level of one finger wrapped around the glass at the bottom. Another definition (from Noah Webster): "nearly an inch." Finger is also the name of a longer unit of length used in cloth measurement, specifically, one eighth of a yard or 4 inches. In English these units have mostly fallen out of use, apart from the common use in distilled drinks and drinking games.