early 15c., "wringing pain in the bowels," from Old French torsion (early 14c.), from Late Latin torsionem (nominative torsio) "a wringing or gripping," from Latin tortionem (nominative tortio) "torture, torment," noun of action from past participle stem of torquere "to twist" (see thwart). Meaning "action or process of twisting as by opposing forces" is first recorded 1540s.
torsion tor·sion (tôr'shən)
A twisting or rotation of a part on its long axis.
Twisting of the cut end of an artery to arrest hemorrhage.
Ocular rotation around the anteroposterior axis.