Avoirdupois

Avoirdupois is a system of weight based on a pound of 16 ounces, used chiefly for ordinary commercial goods. Its units differ from those of the troy system.

Avoirdupois pound: A unit of mass equal to 16 avoirdupois ounces, or exactly 0.45359237 kilograms. This is the system’s defining unit and the basis for its familiar 16-ounce structure.
Medieval weights and measures: The diverse local systems of measurement used across Europe during the Middle Ages. Avoirdupois developed amid the varied regional measures that shaped medieval commerce.
Troy weight: A system of weight traditionally used for precious metals, with a pound of 12 ounces. Its 12-ounce pound contrasts directly with the avoirdupois pound of 16 ounces.
United States customary units: The non-metric system of units used in the United States, including pounds and ounces. Its ordinary pound and ounce measurements follow avoirdupois relationships.
Ounce: A unit of mass or weight whose value depends on the measurement system in which it is used. The avoirdupois ounce is one-sixteenth of its pound, unlike several other ounces.
French language: A Romance language that developed from Latin and is spoken across several continents. The system’s name derives from Old French words associated with goods of weight.
Apothecaries' system: A historical system of weights used in pharmacy, with units related to troy weight. Its specialized medicinal measures differ from avoirdupois measures for ordinary goods.
British imperial units: The measurement system defined by British law in 1824, including the imperial pound and ounce. Its mass units use the avoirdupois pound and ounce.
Avoirdupois dram: A unit equal to one-sixteenth of an avoirdupois ounce, or 27.34375 grains. It subdivides the ounce into a smaller unit within the same system.
Edward III of England: King of England from 1327 to 1377, whose reign included statutory regulation of weights and measures. A 14th-century English statute associated with his reign describes a pound of 16 ounces.

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