What is a millimeter?
A millimeter is a thousandth of a meter (1/1000) which is the SI (International System of Units) unit of length. It is normally used to measure small lengths like the thickness of a sheet of paper or the dimensions of a small object.
One millimeter is approximately equal to 0.03937 inches (about 1/25th). Presicely there are 25.4 millimeters in an inch and it is often used in science and engineering. It is used in countries that have adopted the metric system.
You may come across millimeters when measuring the size of electronic components, jewelry or even the thickness of a fingernail.
What is a furlong?
A furlong is 220 yards or 660 feet, which is exactly 201.168 meters. It is an eighth of a mile.
The origin of the term "furlong" can be traced back to Old English, where "furh" meant "furrow" and "lang" meant "long." This reflects the historical use of furlongs in measuring the length of a furrow in agricultural fields. In horse racing, furlongs are used to measure the distance between the starting point and the finish line. A racecourse typically consists of multiple furlongs, with the most common distances being 5 furlongs (5/8 of a mile) and 8 furlongs (1 mile).
Outside the racecourse the furlong has almost gone. British racing still gives distances in miles and furlongs, so a mile and a quarter is written 1m 2f. Road signs don't use it – they give miles and, for short distances, yards.