| torsion [`tȯr·shǝn] MATHEMATICS The rate of change of the positive direction of the binormal of a space curve with respect to arc length along the curve; its sign is defined as positive if it is in the same direction as the principal normal, and negative if it is in the opposite direction. MECHANICS A twisting deformation of a solid body about an axis in which lines that were initially parallel to the axis become helices. |