tor·sion 
(tôrshən)
(tôrshən)n.
1.
a. The act of twisting or turning.
b. The condition of being twisted or turned.
2. The stress or deformation caused when one end of an object is twisted in one direction and the other end is held motionless or twisted in the opposite direction.
[Middle English torcion, wringing pain in the bowels, from Old French torsion, from Late Latin torsiō, torsiōn-, a wringing pain, variant of Latin tortiō, from tortus, past particple of torquēre, to twist; see TORSADE.]
torsion·al adj.
torsion·al·ly adv.