Definition of torsion in US English:



  • 1The action of twisting or the state of being twisted, especially of one end of an object relative to the other.

    • ‘We have indicated that the salt-bridge stretching mechanism involves solely reorientation of the positively charged polarized bonds due to torsion of the polyene chain at the linkage to Lys - 296.’
    • ‘In addition, the Ramachandran Z-score, which measures deviation of backbone torsion angles from commonly seen distributions, was well within the normal range of values.’
    • ‘The major reason for this was that the barrier joints were weak in torsion and when impacted by a vehicle, instead of sliding over, the barrier pitched allowing the vehicle to readily ride up the side.’
    • ‘As only library rotamers are used for heavy atom conformers, these are near torsion minima and their torsion energies are set to zero.’
    • ‘Axial, shear, and torsion stresses were relatively low compared with bending stresses for both species.’
    • ‘In turn, every backbone torsion angle was tested as a potential hinge point.’
    • ‘The downward shift is attributed to a decrease of the bond order of C 13 = C 14 due to its torsion.’
    • ‘In the human lumbar spine their angulation limits torsion, at a single intervertebral joint, to about 30.’
    • ‘A torsion typical of anamorphosis twists the image, crumples it and alters it, attempting to introduce the eccentrical into the field of view.’
    • ‘Our few preserved large bronze statues make a striking contrast to the many extant statuettes, whose complex movements and marked torsion make them strongly three-dimensional.’
    • ‘As the cantilever executes small torsion resonant oscillations by twisting about its long axis, the cantilever's free end and the AFM tip rotate a very small angle about that axis.’
    • ‘The main difference is that in the present case there is no free rotation around the linker, and so torsion is transmitted.’
    • ‘The hollow-section aluminum control arms, highly rigid in torsion and flex, absorb a large portion of the forces acting on the wheels.’
    • ‘Hydrophobic interactions and other geometrically nonspecific interactions are lumped together and modeled using effective torsion, v, and H-bond to solvent, u, energy terms.’
    • ‘The overall conformational energy of a molecular system is presented as the sum of van-der-Waals interactions, electrostatic interactions, and torsion energies.’
    • ‘The VVA team leaned toward using self-piercing rivets to join components, but after testing the method under impacts and torsion loads found that the rivets alone wouldn't be enough.’
    • ‘These structures are highly polymorphic and the strand polarity and glycosidic torsion angles are affected by the nature of the cations, the connecting loops, the capping bases, and the presence of other bases.’
    • ‘Perhaps the length of the girdle elements was designed precisely to prevent and dampen torsion while making the most of the relatively small vertical motions possible with a lizard-like leg structure.’
    • ‘The intramolecularly averaged torsion angles Î and Î are related quantities because these torsions control the glucose tilt angles.’
    • ‘If the pole has not got sufficient strength, there is a tendency to torsion or slight movement which renders the installation futile.’
    1. 1.1Mathematics The extent to which a curve departs from being planar.
      • ‘The slope of the plot from the absolute temperature against the mean square angular displacements of Trp residues determines an averaged value of the elastic torsion that the protein exerts on its Trp residues.’
      • ‘Because the present calculation is based on the force field method, the calculated result should be taken as expressing the qualitative feature of the torsion potential even if we sometimes mention numerical values.’
      • ‘The torsion of the distal plane relative to the proximal plane is about 60 degrees.’
      • ‘A deeper characterization of a helix is that it is the unique curve in 3-space for which the ratio of curvature to torsion is a constant, a result known as Lancret's Theorem.’
      • ‘The Ferrari measured just under 16,000 ib.ft. per degree of torsion.’
      • ‘The first application as a numerical method, however, was given by Courant in 1943 in his solution of a torsion problem.’
      • ‘Thus, the local curvature and torsion of the ribbon are dependent on the local chemical state.’
      • ‘The fourth and final step is an inspection of each one-dimensional representation, which will therefore reveal the optimum value for the respective torsion.’
      • ‘This situation rather suggests that the fluorescence spectrum is an ensemble average over molecules with different degrees of torsion.’
      • ‘Bending and torsional stiffness are 31% greater than the baseline, with a natural frequency of 25.0 Hz in torsion and 27.8 Hz in vertical bending.’
      • ‘And, yes, the frame is a whole lot stiffer than the predecessor: 2.5 times better in bending, and 2.8 times better in torsion.’
    2. 1.2Zoology (in a gastropod mollusk) the spontaneous twisting of the visceral hump through 180° during larval development.
      • ‘The relatively small single aperture forces the anus to lie close to the mouth, and the gut is bent into a ‘U’ shape or (with gastropods) twisted on account of torsion.’
      • ‘Some species reverse torsion, but evidence of having passed through a twisted phase can be seen in the anatomy of these forms.’
      • ‘The combination of hinge teeth with a cementing habit is interpreted as a defense strategy inhibiting torsion of the valves as well as manipulation of the animal as a whole.’
      • ‘Using a functional definition, with Gastropoda defined solely by the presence of torsion, this is the clade that represents the class as defined by Cuvier.’
      • ‘They also questioned the relationship between torsion and muscle scar position by noting that retractor muscles form after torsion on at least some gastropods.’
      • ‘Of all molluscan clades, only the gastropods undergo torsion.’
      • ‘The columellar location of the gastropod retractor muscle is thought to be an effect of torsion.’
      • ‘This is because, unlike gastropods, ‘Tergomyans’ have not undergone torsion.’
      • ‘A major characteristic of gastropods is the torsion of their bodies: the posterior part of the mantle cavity is rotated laterally and anteriorly so that it comes to lie above the head.’
      • ‘Numerous hypotheses exist positing torsion as either a larval or adult adaptation, but none are entirely satisfactory.’
      • ‘Figure 4 shows a fiber in a single lamella being stretched by torsion.’


Late Middle English (as a medical term denoting colic or in the sense ‘twisting’ (especially of a loop of the intestine)): via Old French from late Latin torsio(n-), variant of tortio(n-) ‘twisting, torture’, from Latin torquere ‘to twist’.