This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. The state of being curved like the inner surface of a sphere.

n. A surface or structure configured in such a curve: "a perfect concavity of white sand lined with palm . . . trees” ( Islands).

n. The state of being concave

n. A concave structure or surface

n. A concave surface, or the space bounded by it; the state of being concave.

n. The state of being concave; hollowness.

n. A concave surface, or the space contained in it; the internal surface of a hollow curved body, or the space within such body; any hollow space which is more or less spherical.

n. the property possessed by a concave shape

n. a shape that curves or bends inward

"The central part of the posterior surface presents a deep concavity which is moulded on the vertebral column and crura of the diaphragm."

convexity   

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