heterostatic

from The Century Dictionary.

• Pertaining to three axes which can be drawn at every point of every elastic body such that, denoting them by the letters x, y, z, if a very small cube be cut out of the body with its edges parallel to those axes, and if the cube be twisted by a given amount round x, then a normal stress will be produced upon the faces to which x is normal equal to the tangential stress which would be produced round z by an equal amount of twisting round y.
• Applied to instruments for measuring potential by electrostatic methods in which electrification other than that to be tested is made use of.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Of or pertaining to heterostasis