An ounce (oz) is a unit of weight in the U.S. customary system of measurement.
16 ounces = 1 pound
An ounce, within the context of fluids, is also called a fluid ounce, is a unit of capacity in the U.S. customary system of measurement.
8 fluid ounces = 1 cup
Did you know?
A hen's egg, such as one you might eat for breakfast, weighs about 2 ounces. A hummingbird's egg, however, is very tiny. It weighs about of an ounce.
See also U.S. customary units, fluid ounces.