Crystall.
any of four points, lines, or planes of a crystal: a center of symmetry, a reflection plane, a rotation axis, or a rotation-inversion axis.
Crystall.
any of four points, lines, or planes of a crystal: a center of symmetry, a reflection plane, a rotation axis, or a rotation-inversion axis.
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012