Astatic

a.

1.

(Magnetism) 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 galvanometers.

Adj.

1.

astatic - not static or stable

changeable, changeful