con·cav·i·ty /kɑnˈkævəti/
  中央凹陷,凹窪,凹狀
  con·cav·i·ty /kɑnˈkævətɪ/ 名詞
  凹,凹面,凹度
  Con·cav·i·ty n.; pl. Concavities   A concave surface, or the space bounded by it; the state of being concave.
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  concavity
       n 1: a shape that curves or bends inward [syn: concave shape, incurvation,
             incurvature]
       2: the property possessed by a concave shape [syn: concaveness]