Source : Webster's Revised Unabridged Dictionary (1913)

Avoirdupois \Av`oir*du*pois"\ ([a^]v`[~e]r*d[-u]*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.]

   {Avoirdupois weight}, a system of weights by which coarser
      commodities are weighed, such as hay, grain, butter,
      sugar, tea.

   Note: The standard Avoirdupois pound of the United States is
         equivalent to the weight of 27.7015 cubic inches of
         distilled water at 62[deg] 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).

Source : WordNet®

avoirdupois
     n 1: a system of weights based on the 16-ounce pound (or 7,000
          grains) [syn: {avoirdupois weight}]
     2: excess bodily weight; "she found fatness disgusting in
        herself as well as in others" [syn: {fatness}, {fat}, {blubber}]
        [ant: {leanness}]