凹おう面めん

noun

concave surface; concavity

Refers to a surface that curves inward, like the inside of a bowl. Often used in technical contexts such as optics or geometry.

• 凹おう面めん鏡きょうは光ひかりを集あつめるのに使つかわれる。

  Concave mirrors are used to collect light.

noun which may take the genitive case particle 'no'

concave

Used as a modifier (with の) to describe something having a concave shape. Common in compound terms like 凹面鏡 (concave mirror).