noun
angle of refraction
Technical term in optics and physics; used in scientific contexts.
光が水に入るとき、屈折角は入射角より小さくなる。
When light enters water, the angle of refraction becomes smaller than the angle of incidence.
Compound of 屈折 (refraction) and 角 (angle). The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning.