the.com/avoirdupois
The weight system that quietly decides your pound has sixteen ounces, not twelve.
means The standard system of weights used for everyday goods, where a pound equals sixteen ounces; also, jokingly, a person's heftiness.
from From Old French aveir de peis, goods sold by weight, mangled by English mouths into a word nobody can spell on the first try.
Rival systemTroy weight handles gold; avoirdupois handles groceries.
Ounce gapAvoirdupois ounces are lighter than troy ounces.
Sneaky usageNow polite code for a person's bulk.