AN n. 2 definitions
This word is properly an adjective, but is commonly called the indefinite article. It is used before nouns of the singular number only, and signifies one, or any, but somewhat less emphatically. In such expressions as "twice an hour," "once an age," a shilling an ounce (see 2d A, 2), it has a distributive force, and is…
ANA adv. 3 definitions
Of each; an equal quantity; as, wine and honey, ana (or, contracted, aa), ., that is, of wine and honey, each, two ounces. An apothecary with a . . . long bill of anas. Dryden.