Definition:Avoirdupois/Ounce

Definition
The ounce is an imperial unit of mass.
 * $1$ ounce $= \dfrac 1 {16}$ pound $= 437 \cdotp 5$ grains $= 28 \cdotp 34952 \, 3125$ grams.

This is the international avoirdupois ounce which is in common use.