Note:  Do not rely on this information. It is very old.


Avoirdupois (old Fr. aveir de pois, lit. goods of weight), the system of weights applied in the United Kingdom to all goods except medicines, precious metals, and precious stones. The grain is the foundation of the system. A cubic inch of water at standard temperature weighs 252.458 grains; 7,000 of such grains make a pound avoirdupois (=453.6 grams in the French metric system). The system was introduced from Bayonne about 1300, and is of Spanish origin. It is also in use in the United States, except that usually the hundredweight there is 100 lbs., and the ton 2,000 lbs., instead of, as in Great Britain, 112 lbs. and 2,240 lbs. respectively.