Avoirdupois

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Avoirdupois (; abbreviated avdp.) is a measurement system of weights that uses pounds and ounces as units. It was commonly used in the 13th century AD and was updated in 1959. In 1959, by international agreement among countries that used the pound as a unit of mass, the International Avoirdupois Pound was fixed at the modern definition of exactly 0.45359237 kilograms.. It remains the everyday system of weights used in the United States, and is still used, in varying degrees, in everyday life in the United Kingdom and some former British colonies, despite their official adoption of the metric system. The avoirdupois weight system's general attributes were originally developed for the international wool trade in the Late Middle Ages, when trade was in recovery. It was historically based on a physical standardized pound or "prototype weight" that could be divided into 16 ounces. There were a number of competing measures of mass, and the fact that the avoirdupois pound had three even numbers...

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