Finger (unit)

A finger is any of several units of measurement that are approximately the width of an adult human finger.
The digit, also known as digitus or digitus transversus, dactyl or dactylus, or finger's breadth of an inch or of a foot.
In medicine and related disciplines the fingerbreadth 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 : "nearly an inch."
Finger is also the name of a longer unit of length, used historically in cloth measurement, to mean one eighth of a yard or 4 inches. Again, which finger and whose finger, is not defined.
These units have no legal status but remain in use for 'rough and ready' comparisons.