reentering polygon
- noun
- /ˌriːˈɛn.tər.ɪŋ ˈpɒl.ɪ.ɡən/
- Specialized
- A reentering polygon has at least one angle that measures more than 180 degrees.
Examples
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Unlike convex shapes, a reentering polygon can have inward-pointing angles.
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An example of a reentering polygon is a star, which has angles that point inward.
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A star-shaped figure is a classic example of a reentering polygon.
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The architect designed the courtyard in the shape of a reentering polygon for aesthetic effect.
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A reentering polygon can create complex shapes.
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The architect designed a reentering polygon for the new park.
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In geometry class, we learned that a reentering polygon can appear star-shaped.
Synonyms
A flat shape with straight sides that has one or more inward angles greater than 180 degrees, like a star
A polygon with at least one angle of more than 180 degrees that has a part pointing inward
How Concave
Surface Forms
Morphology
A B1 learner who knows 'reenter' (=enter again) and 'polygon' (a many-sided shape) would not be able to infer the technical geometric sense of a shape with interior angles >180°; the intended meaning relies on the specialized notion of a 'reentrant' (inward-pointing) angle rather than the everyday sense of entering again. This is domain-specific vocabulary and a semantic shift from the literal constituents, so prior exposure or technical knowledge is required.
Etymology
Reentering polygon names a many-sided shape that folds back into itself: some corners point inward instead of outward. Here reentering suggests the sides 're-enter' the shape and polygon means a many-sided figure, so the term means a polygon with one or more angles larger than a straight line, more than 180 degrees.