Ounce

The ounce is the name for a number of different units of mass, and, confusingly, volume. See Imperial system of units and U.S. customary units for more about the frameworks within which these units are defined.

See:

• avoirdupois ounce[?] defined by the avoirdupois system of mass (see pound). There are 16 ounces in the avoirdupois pound. The avoirdupois ounce is approximately 28.3 g.
• troy ounce defined by the troy system of mass[?]. In troy weight, unlike the more common avoirdupois system, there are 12 ounces in a pound, rather than 16, and a troy pound is 5760 grains (approx. 373.24 grams), rather than 7000 (approx 453.59 grams). Note: at roughly 31.1 g, the troy ounce is about 10% more than the more common avoirdupois ounce defined by the avoirdupois system of mass.

The Dutch term ons is a unit of mass that is considerably more, 100 grams.

There are also two versions of the fluid ounce[?], units of volume, of 28.4 and 29.6 ml.

The symbol for ounce is ℥

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Ounce is also another name for the snow leopard.