[adj., v. kon-keyv, kon-keyv; n. kon-keyv] 
adjective, noun, verb, -caved, -cav⋅ing.| 1. | curved like a segment of the interior of a circle or hollow sphere; hollow and curved. Compare convex (def. 1). |
| 2. | Geometry. (of a polygon) having at least one interior angle greater than 180°. |
| 3. | Obsolete. hollow. |
| 4. | a concave surface, part, line, or thing. |
| 5. | Machinery. a concave piece, as one against which a drum rotates. |
| 6. | to make concave. |
concave con·cave (kŏn-kāv', kŏn'kāv')
adj.
Curved like the inner surface of a sphere. n.
A concave surface, structure, or line.
| concave (kŏn'kāv') Pronunciation Key
Curved inward, like the inside of a circle or sphere. |
keɪv