Astatic

A·stat·ic

Astatic

a.
  1. 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. (Magnetism)

Phrases & Compounds

Astatic pair
a pair of magnetic needles so mounted as to be nearly or quite astatic, as in some galvanometers.