Avoirdupois

It is still used, in varying degrees, in everyday life in the United Kingdom, Canada, Australia[citation needed], and some other former British colonies, despite their official adoption of the metric system.

It was historically based on a physical standardized pound or "prototype weight" that could be divided into 16 ounces.

[3] The use of this unofficial system gradually stabilized[b] and evolved, with only slight changes in the reference standard or in the prototype's actual mass.Over time, the desire not to use too many different systems of measurement allowed the establishment of "value relationships", with other commodities metered and sold by weight measurements such as bulk goods (grains, ores, flax) and smelted metals; so the avoirdupois system gradually became an accepted standard through much of Europe.

In the modern day, this is evident in the small difference between United States customary and British Imperial pounds.

[3][4] The word avoirdupois is from Anglo-Norman French aveir de peis (later avoir du pois), literally "goods of weight" (Old French aveir, as verb meaning "to have" and as noun meaning "property, goods", comes from the Latin habere, "to have, to hold, to possess something"; de = "from"/"of", cf.

[5][6]) This term originally referred to a class of merchandise: aveir de peis, "goods of weight", things that were sold in bulk and were weighed on large steelyards or balances.

Inconsistent orthography throughout history has left many variants of the term, such as haberty-poie and haber de peyse.

The rise in use of the measurement system corresponds to the regrowth of trade during the High Middle Ages after the early crusades, when Europe experienced a growth in towns, turned from the chaos of warlordism to long-distance trade, and began annual fairs, tournaments and commerce, by land and sea.

[citation needed] However, the main weight system, used for coinage and for everyday use, was based on the 12-ounce tower pound of 5400 grains.

[12] The earliest known occurrence of the word "avoirdupois" (or some variant thereof) in England is from a document entitled Tractatus de Ponderibus et Mensuris ("Treatise on Weights and Measures").

This document is listed in early statute books under the heading 31 Edward I dated 2 February 1303.

[13] Initially a royal memorandum, it eventually took on the force of law and was recognized as a statute by King Henry VIII and Queen Elizabeth I.

"[16] & acorde qe deſore en auant vn meſure & vn pois ſoit parmy toute Engleterre & qe le Treſorer face faire certaines eſtandardz de buſſel de galon de poys darreiſne & les face mander en cheſcune countee par la ou tielx eſtandardz ne ſont pas auant ces hures mandez (4) it is assented and accorded, That from henceforth one Measure and one Weight shall be throughout England; (5) and that the Treasurer cause to be made certain Standards of Bushels, Gallons, of Weights of Auncel, and send the same into every County where such Standards be not sent before this Time; The second major development is the statute 25 Edw 3 Stat.

"[17] qe le ſak de leine ne poiſe qe vint & ſys peres & cheſcun pere poiſe quatorze livres so that the Sack of Wooll weigh no more but xxvi.

Finely crafted pan balance or scales with boxed set of standardized gram weights sequenced in units of mass. Such scales are used to make the most accurate of fine measurements, such as in the needs of empirical chemistry.
Robust weights like these hexagonal decimal-scaled antiques were used for trade into the late 20th century.
The units first became used by wool traders in the Kingdom of England and the Low Countries during the end of the High Middle Ages , as population growth and the Renaissance gave rise to an increasingly numerous town population and a newly established middle class.
Comparison of the relative sizes of avoirdupois, Troy, tower, merchant and London pounds.