As \As\, n.; pl. Asses. [L. as. See Ace.]

1. A Roman weight, answering to the libra or pound, equal to nearly eleven ounces Troy weight. It was divided into twelve ounces.

2. A Roman copper coin, originally of a pound weight (12 oz.); but reduced, after the first Punic war, to two ounces; in the second Punic war, to one ounce; and afterwards to half an ounce.

Source: Webster's Revised Unabridged Dictionary (1913)