AN n.
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…
ASTATIC a.
Having little or no tendency to take a fixed or definite position or direction: thus, a suspended magnetic needle, when rendered astatic, loses its polarity, or tendency to point in a given direction. Astatic pair (Magnetism), a pair of magnetic needles so mounted as to be nearly or quite astatic, as in some galvanomet…