- Of a plane figure, a solid or a set of points that is not convex, for example, hollowed out like the inner curve of a circle or sphere. An arc of a curve is concave toward a point or line if every segment of the arc cut off by a secant lies on the opposite side of the secant from the point or line. A concave polygon always has an interior angle greater than 180 degrees.
- Thin, flat, circular objects of any material.
- Refers to the cultures of the continent of North America, which is bounded by the Atlantic Ocean, the Pacific Ocean, the Arctic Circle, and Central America. In classifications schemes based on physical geography, Central America, and North America are parts of the same continent.
- Of limited size or comparatively restricted dimensions, especially in comparison with other things of the same kind.
- General term for rock that has been cut, shaped, crushed, or otherwise formed for use in construction or other purposes. Includes the specific archaeological and anthropological sense of individual stones which may be decorated or ornamented and which may be used in ritual contexts. These are usually not carved or dressed, and so differ from sculptures made from stone.
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