This category needs to be specified more precisely! The word "round" is used colloquially in many ways, mostly in the sense of beeing “round like a circle” (→circular or ring-shaped), “round like a roll or drum” (→cylindrical) or “round like a ball” (→spherical) and often only as a distinction from the “regular” shape of the objects, e.g. beeing “round, not rectangular” or beeing “round, not flat” or being “round and not having edges”. So possible 2D-meanings of “round” are: