A system of mass units use to measure precious metals (c.f. avoirdupois system of units). While there are 16 avoirdupois ounces in one avoirdupois pound-mass, there are only 12 troy ounces in one troy pound. However, the troy and avoirdupois units of grain are equal. The system is summarized in the following table.
References
Woolf, H. B. (Ed. in Chief). Webster's New Collegiate Dictionary. Springfield, MA: Merriam, p. 1329, 1980.
