- helicoid⇄adj. like a helix; curved spirally, as certain univalve shells are; spiral.
- helicoid⇄adv. helicoidally.
- helicoid⇄helicoid, noun, adjective.
(Geometry.) - helicoid⇄noun a surface in the form of a coil or screw; a warped surface generated by a straight line moving so that it always passes through or touches a fixed helix and is parallel to a fixed plane.