平へい凹おうレンズへいおうレンズMeanings1nounplano-concave lensA lens with one flat surface and one concave surface. Used in optics, often for beam expansion or correction.See also: 平凸レンズ平へい凹おうレンズは、平へい行こう光こう線せんを発はっ散さんさせるの