American Dictionary of the English Language

OUNCE, noun ouns. [Latin uncia, the twelfth part of any thing; Gr; but the Greek is from Latin. Inch is from the same root, being the twelfth part of a foot.]

1. A weight, the twelfth part of a pound troy, and the sixteenth of a pound avoirdupois. In troy weight, the ounce is 20 pennyweights, each of 24 grains.

2. An animal of the genus Felis. [See Once.]