Ounce (ouns), n. [F. once, fr. L. uncia a twelfth, the twelfth part of a pound or of a foot: cf. Gr. ὄγκοσ bulk, mass, atom. Cf. 2d Inch, Oke.] 1. A weight, the sixteenth part of a pound avoirdupois, and containing 437½ grains.
2. (Troy Weight) The twelfth part of a troy pound.
☞ 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.
By ounces hung his locks that he had. Chaucer.
Fluid ounce. See under Fluid, n.