Av`oir*du*pois" (ăv`&etilde;r*d&usl;*poiz"), n. & a. [OE. aver de peis, goods of weight, where peis is fr. OF. peis weight, F. poids, L. pensum. See Aver, n., and Poise, n.] 1. Goods sold by weight. [Obs.]

2. Avoirdupois weight.

3. Weight; heaviness; as, a woman of much avoirdupois. [Colloq.]

&fist; The standard Avoirdupois pound of the United States is equivalent to the weight of 27.7015 cubic inches of distilled water at 62° Fahrenheit, the barometer being at 30 inches, and the water weighed in the air with brass weights. In this system of weights 16 drams make 1 ounce, 16 ounces 1 pound, 25 pounds 1 quarter, 4 quarters 1 hundred weight, and 20 hundred weight 1 ton. The above pound contains 7,000 grains, or 453.54 grams, so that 1 pound avoirdupois is equivalent to 1 31-144 pounds troy. (See Troy weight.) Formerly, a hundred weight was reckoned at 112 pounds, the ton being 2,240 pounds (sometimes called a long ton).

• the official system of weights used in UK between 1856 and 1963. It had been the customary system in London since AD 1300.
  
• the official system of weights used in USA between 1866 and 1959.
  
• weight; heaviness;
        he has a lot of avoirdupois