The Collaborative International Dictionary
Helicoid \Hel"i*coid\, a. [Gr. ?; ?, ?, spiral + ? shape: cf. F. h['e]lico["i]de. See Helix.]
Spiral; curved, like the spire of a univalve shell.
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(Zo["o]l.) Shaped like a snail shell; pertaining to the Helicid[ae], or Snail family.
Helicoid parabola (Math.), the parabolic spiral.
Helicoid \Hel"i*coid\, n. (Geom.) A warped surface which may be generated by a straight line moving in such a manner that every point of the line shall have a uniform motion in the direction of another fixed straight line, and at the same time a uniform angular motion about it.
Wiktionary
a. Having the form of a flattened helix n. (context mathematics English) A minimal surface in the form of a flattened helix.
Wikipedia
The helicoid, after the plane and the catenoid, is the third minimal surface to be known.
Usage examples of "helicoid".
As if standing sentinel, a helicoid towered there, a hundred meters into heaven.