D defs.my
Entry 2 senses Webster, 1913

Torsion

/tôr'-shən/ · Tor·sion · IPA /ˈtor.ʃɪn/
01 n. The act of turning or twisting, or the state of being twisted; the twisting or wrenching of a body by the exertion of a lateral force tendi…
  1. 1.
    The act of turning or twisting, or the state of being twisted; the twisting or wrenching of a body by the exertion of a lateral force tending to turn one end or part of it about a longitudinal axis, while the other is held fast or turned in the opposite direction.
  2. 2.
    That force with which a thread, wire, or rod of any material, returns, or tends to return, to a state of rest after it has been twisted; torsibility.(Mech.)
Phrases & compounds
Angle of torsion — the indefinitely small angle between two consecutive osculating planes of a curve of double curvature.
Moment of torsion — the moment of a pair of equal and opposite couples which tend to twist a body.
Torsion balance — an instrument for estimating very minute forces, as electric or magnetic attractions and repulsions, by the torsion of a very slender wire or fiber having at its lower extremity a horizontal bar or needle, upon which the forces act.
Torsion scale — a scale for weighing in which the fulcra of the levers or beams are strained wires or strips acting by torsion.