\begin{definition}[Definition:Avoirdupois/Ounce]
The '''ounce''' is an avoirdupois unit of mass.
:$1$ '''ounce avoirdupois''' $= 16$ drams $= 437 \cdotp 5$ grains $= 28 \cdotp 34952 \, 3125$ grams.
{{begin-eqn}}
{{eqn | o = 
      | r = 1
      | c = '''ounce avoirdupois'''
}}
{{eqn | r = 16
      | c = drams
}}
{{eqn | r = 437 \cdotp 5
      | c = grains
}}
{{eqn | r = 28 \cdotp 34952 \, 3125
      | c = grams
}}
{{end-eqn}}
The gram equivalent is defined to be exact.
\end{definition}