Ounce \Ounce\, n. [F. once, fr. L. uncia a twelfth, the twelfth part of a pound or of a foot: cf. Gr. ? bulk, mass, atom. Cf. 2d Inch, Oke.]

1. A weight, the sixteenth part of a pound avoirdupois, and containing 437? grains.

2. (Troy Weight) The twelfth part of a troy pound.

Note: The troy ounce contains twenty pennyweights, each of twenty-four grains, or, in all, 480 grains, and is the twelfth part of the troy pound. The troy ounce is also a weight in apothecaries' weight. [Troy ounce is sometimes written as one word, troyounce.]

3. Fig.: A small portion; a bit. [Obs.]

By ounces hung his locks that he had. --Chaucer.

Fluid ounce. See under Fluid, n.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Ounce \Ounce\, n. [F. once; cf. It. lonza, Sp. onza; prob. for lonce, taken as l'once, fr. L. lynx, Gr. ?, or an (assumed) fem. adj. lyncea, from lynx. Cf. Lynx.]

(Zo["o]l.) A feline quadruped (Felis irbis, or uncia) resembling the leopard in size, and somewhat in color, but it has longer and thicker fur, which forms a short mane on the back. The ounce is pale yellowish gray, with irregular dark spots on the neck and limbs, and dark rings on the body. It inhabits the lofty mountain ranges of Asia. Called also once.

Source: Webster's Revised Unabridged Dictionary (1913)