gyroidal

from The Century Dictionary.

• Spiral in arrangement or in movement.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Spiral in arrangement or action.
• adjective (Crystallog.) Having the planes arranged spirally, so that they incline all to the right (or left) of a vertical line; -- said of certain hemihedral forms.
• adjective (Opt.) Turning the plane of polarization circularly or spirally to the right or left.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Spiral in arrangement or action.
• adjective 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.
• adjective Turning the plane of polarization circularly or spirally to the right or left.