concave
concave[ˈkɒnkeɪv]adjective- having an outline or surface that curves inwards like the interior of a circle or sphere
(轮廓,表面)凹的。 比较 convex (义项1)
派生concavelyadverbconcavitynoun语源- late Middle English: from Latin concavus, from con- 'together' + cavus 'hollow'
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