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Assuming there is a name for this, what is it? I have looked through the list names of shapes in Wikipedia, but those seem all to be either polygons (all straight-sided) or all curves, none that are a mix of lines and arcs. The closest I have found is "stadium", but that obviously has both ends convex, not to mention that the arcs are semicircles.

shape with parallel sides and arc ends, one convex and one concave

The object in the photo is part of a set of card scrapers, which are used for finishing wood; sets commonly include also a rectangle and a "goose neck". Product listings usually call these "curved" which is not a great name.

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    $\begingroup$ A "norman window" is the closest named figure that I can think of. $\endgroup$
    – Jam
    Commented Oct 25, 2022 at 22:12
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    $\begingroup$ I think you’re stuck with the annoying fact that there are fewer established names than there are possible shapes to give names to. You might try “convex-concave-ended trapezoid”, but that’s ugly ugly. $\endgroup$
    – Lubin
    Commented Oct 25, 2022 at 22:13
  • $\begingroup$ I found a product listing that describes this product as “1 concave/convex scraper”. $\endgroup$
    – Dan
    Commented Oct 25, 2022 at 22:17
  • $\begingroup$ An arc sheared rectangle? $\endgroup$
    – 2'5 9'2
    Commented Oct 26, 2022 at 6:24

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Probably the shortest common description in English is a rectangle with one side curved convex and the opposite side curved concave. On Amazon, we find a similar item to yours described as

Fulton Scraper Burnisher with 6 Piece Multi-Shaped Scraper Set 3 Rectangle 1 Beveled 1 Curved (Convex and Concave) and 1 Gooseneck Scraper

This shape is used as the symbol for "stored data" in flowcharts since it resembles a cylinder viewed from one side. However, none of the websites describing the various flowchart symbols gives it a name.

If the rectangle's straight sides are thin, this shape is often described by the term "warped", as in plywood or steel sheets which are warped. In lens making, this shape may be described as "meniscus", but that term generally seems to apply to shapes other than this when not referring specifically to lenses.

This website from Germany calls it a "curved rectangle". However, the term "curved rectangle" is used by others to describe either a rectangle with curved corners, or a rectangle which is bent. I was hoping to at least find a German name, but the German equivalent page calls it "Gekrümmtes Rechteck", which doesn't turn up anything similar on Google Images.

In conclusion, if this shape does have a name, it's very obscure.

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  • $\begingroup$ A well-researched denial of existence is about the best I can hope for then; thank you. $\endgroup$
    – Wil Cooley
    Commented Oct 31, 2022 at 23:24

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