Ounce

Ounce. Ounce and Inch are doublets, both being derived from the Latin Uncia, the twelfth part of any weight or measure. An ounce is the twelfth part of a pound troy, but the sixteenth part of a pound avoirdupois. In the former it contains 480 grains (20 dwt.), in the latter 437-1/2 grains.