rotation axis

rotation axis

[rō′tā·shən ‚ak·səs] (crystallography) A symmetry element of certain crystals in which the crystal can be brought into a position physically indistinguishable from its original position by a rotation through an angle of 360°/ n about the axis, where n is the multiplicity of the axis, equal to 2, 3, 4, or 6. Also known as symmetry axis.