An ounce is
an imperial unit for measuring mass. 16 ounces equal 1 pound. The
ounce is a unit of mass in a number of different systems, including various
systems of mass that form part of the imperial and United States
customary systems. Its size can vary from system to system. The
most commonly used ounces today are the international avoirdupois
ounce and the international troy ounce.