反そり返かえり

noun

warp; bend; retroflection

Describes the state or degree of being warped, bent, or curved backward. Often used in technical contexts for materials, but also for body posture or shape.

• この板いたは反そり返かえりがひどい。

  This board has a severe warp.

• 背せ中なかの反そり返かえりを直なおすストレッチ。

  A stretch to correct the backward bend of the back.