A furlong is a Biblical unit of measurement found in the New Testament.  It is approximately 200 yards or 182.9 meters.

A furlong is the length of an ancient Greek racetrack, which is 1/8 of a Roman mile. 

The furlong is usually an approximate distance but the dimensions of the New Jerusalem in Revelation 21:16 are recorded to be measured 12,000 stadia (furlong) long and wide.