Furlong (Sax. far or fur and long), an old English measure of 40 rods or poles, equivalent to 1/8 of a mile. In Ireland it is 0.15 of a mile, and in Scotland 0.1409. In the United States the measure is not in use. As a superficial measure, a furlong in Great Britain is generally 10 acres, according to the acre of different counties; but it was formerly used for a piece of land of no particular dimensions.