Avoirdupois
The 
avoirdupois system is a system of weights defining terms such as 
pound and 
ounce. It is the everyday system of weight used in the 
United States, and was used in the 
United Kingdom and elsewhere until 
metrication. It is considered more modern and standardised than the alternative 
troy or "apothecary" system. 
See also: Imperial unit and US customary units.
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