ALTERNATION n.
The reciprocal succession of things in time or place; the act of following and being followed by turns; alternate succession, performance, or occurrence; as, the alternation of day and night, cold and heat, summer and winter, hope and fear.
ANA adv.
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.