A measure of length, the twelfth part of a foot, commonly
   subdivided into halves, quarters, eights, sixteenths, etc., as among
   mechanics. It was also formerly divided into twelve parts, called
   lines, and originally into three parts, called barleycorns, its length
   supposed to have been determined from three grains of barley placed end
   to end lengthwise. It is also sometimes called a prime ('), composed of
   twelve seconds (''), as in the duodecimal system of arithmetic.