GYROIDAL
Etymology
Adjective
gyroidal (not comparable)
Spiral in arrangement or action.
(crystallography) Having the planes arranged spirally, so that they all incline to the right (or left) of a vertical line; said of certain hemihedral forms.
Turning the plane of polarization circularly or spirally to the right or left.
Source: Wiktionary
Gy*roid"al, a. Etym: [Gr. -oid + -al.]
1. Spiral in arrangement or action.
2. (Crystallog.)
Definition: Having the planes arranged spirally, so that they incline all
to the right (or left) of a vertical line; -- said of certain
hemihedral forms.
3. (Opt.)
Definition: Turning the plane of polarization circularly or spirally to the
right or left.
Source: Webster’s Unabridged Dictionary 1913 Edition