Gyroidal \Gy*roid"al\ (j[-i]*roid"al), a. [Gr. gy^ros circle +
-oid + -al.]
1. Spiral in arrangement or action.
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2. (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.
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3. (Opt.) Turning the plane of polarization circularly or
spirally to the right or left.
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