enter image description here

Not sure what shape this is I can’t find it anywhere

  • 3
    Excuse me, but you already have it, so why should you find it? If it happens that you must find at least one usage for reasons that do not depend on your will, start from the cross-section profile of double concave lens.
    – user82991
    Sep 27, 2022 at 21:20
  • 4
    Aka the cross-section of a bi-concave lens. What do you expect to learn about this shape?
    – Wolff
    Sep 27, 2022 at 21:36
  • When rotated 90 degrees it can be used as a cartoonish simplification of bow tie. It could as well be the mouth profile of a person who is just getting the final prize for his efforts. That happens in an electric chair. But if it must be something visual like the lens, it could be the mirror profile of a bi-directional Newton reflector telescope which can be used to look to 2 opposite directions at the same time. Or the outline of a business logo of the maker of curved ultra-wide tv-screens.
    – user82991
    Sep 27, 2022 at 22:22
  • 1
    This seems like more of a language question than a design question. You don’t need to know the name of a shape to design with it, after all. I have a nagging feeling I know what this shape is called, but I can’t bring it to mind. For lack of a better word, it’s roughly a spool shape. You’ll probably get better answers on English Language & Usage, though. Sep 27, 2022 at 23:04
  • Adding context to your question would greatly increase the quality of it Sep 28, 2022 at 1:31

1 Answer 1


It can be "concave icon" in some icon collection. It can also be the silhouette of a 3D surface named hyperbolic hyperboloid. There are also other types of hyperboloids. See more of them here https://en.wikipedia.org/wiki/Hyperboloid

If you want to draw one you can probably get a visually good enough version by intersecting a couple of identical ellipses and a rectangle:

enter image description here

If the max. curvature should be in the middle rotate the ellipses 90 degrees. Use circles for constant curvature.

As a flat 2D image of a 3D item it can also be a thin rectangular sheet bent to parabolic shape and seen from the concave side with strong perspective

enter image description here

In the middle it has got shading and in the right it's seen from a different direction with less extreme perspective. Illustrator shows the sideways profile (=the actual extruded curve) as blue at the same time.

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