n.1 twisting, esp. of one end of a body while the other is held fixed.
2 Math. the extent to which a curve departs from being planar.
3 Bot. the state of being twisted into a spiral.
4 Med. the twisting of the cut end of an artery after surgery etc. to impede bleeding.
Phrases and idioms:
torsion balance an instrument for measuring very weak forces by their effect upon a system of fine twisted wire. torsion bar a bar forming part of a vehicle suspension, twisting in response to the motion of the wheels, and absorbing their vertical movement. torsion pendulum a pendulum working by rotation rather than by swinging.
Derivatives:
torsional adj. torsionally adv. torsionless adj.
Etymology: ME f. OF f. LL torsio -onis f. L tortio (as TORT)