中なか高だか

noun which may take the genitive case particle 'no'

convex; bulging in the middle

Describes a shape that is raised or swollen in the center, such as a convex lens or a surface that is higher in the middle than at the edges. Often used in technical or descriptive contexts.

• このレンズは中なか高だかになっている。

  This lens is convex.

• 板いたが湿しっ気けで中なか高だかに反そった。

  The board warped, bulging in the middle due to moisture.