両りょう凸とつ

noun, noun which may take the genitive case particle 'no'

biconvex

Technical term used in optics and geometry to describe a lens or shape that is convex on both sides.

• 両りょう凸とつレンズは光ひかりを集あつめるのに使つかわれる。

  A biconvex lens is used to focus light.