Definition:Apothecaries' Weights and Measures/Mass/Ounce

Definition
The apothecaries' ounce is an apothecaries' unit of mass.
 * $1$ apothecaries' ounce $= \dfrac 1 {12}$ apothecaries' pound $= 480$ grains $\approx 31 \cdotp 1$ grams.

It weighs approximately $\approx 1 \cdotp 1$ ounces avoirdupois.