furlong

From Middle English furlong, forlong (“unit of distance about one-eighth of a mile; quantity of land equal to one square furlong; racetrack for foot races; foot race”) [and other forms], from Old English furlang, furlung, from furh (“a furrow”) (ultimately from Proto-Indo-European *perḱ- (“to dig; to open; to rip up”) + lang (“long”, adjective) (ultimately from Proto-Indo-European *dlongʰos (“long”)), originally the typical length of a furrow in an average field.