noun
concave polygon; non-convex polygon
Technical geometry term for a polygon with at least one interior angle greater than 180 degrees. Contrasts with 凸多角形 (convex polygon).
See also: 凸多角形
凹多角形は少なくとも一つの内角が180度を超える。
A concave polygon has at least one interior angle exceeding 180 degrees.
凸多角形 is a convex polygon where all interior angles are less than 180 degrees, the opposite of 凹多角形.
Compound of 凹 (concave) + 多角形 (polygon). A straightforward technical term.