concave lens
A lens that curves inward, used in physics, optics, and eyeglasses for nearsightedness.
凹レンズは近視の矯正に使われる。
Concave lenses are used to correct nearsightedness.
物
We measured the focal length of a concave lens in physics class.
Compound of 凹 (おう, 'concave') and レンズ (from English 'lens').