screw axis

noun Crystallography.
  1. a symmetry element of a space group such that a rotation of the lattice about the axis and a translation of the lattice some fraction of the lattice's unit distance brings the lattice back to its original position.

Origin of screw axis

First recorded in 1900–05
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018