AVOIRDUPOIS or AVERDUPOIS (from the French avoir de pois, goods of weight), the name of a system of weights used in Great Britain and America for all commodities except the precious metals, gems and medicines. The foundation of the system is the grain. A cubic inch of water weighs 252-458 grains. Of this grain 7,00o now (see MEASURES AND WEIGHTS) make a pound avoirdupois. This pound is divided into 16 oz., and these ounces into 16 drachms.