Emily Dickinson Lexicon

AS, n. [L.]

1. A Roman weight of 12 ounces, answering to the libra or pound.
2. A Roman coin, originally of a pound weight; but reduced, after the first Punic war, to two ounces; in the second Punic War, to one ounce; and by the Papirian law, to half an ounce. It was originally stamped with the figure of a sheep, sow, or ox; and afterward with a Janus, on one side, and on the reverse, a rostrum or prow of a ship.
3. An integer; a whole or single thing. Hence the English ace. Hence the Romans used the word for the whole inheritance; hæres ex asse, an heir to the whole estate. – Encyc.