noun
invisible ray
Technical term used in physics and optics for electromagnetic radiation outside the visible spectrum, such as ultraviolet or infrared rays.
紫外線は不可視光線の一種です。
Ultraviolet rays are a type of invisible ray.
Refers to visible light rays, the opposite of 不可視光線.
Compound of 不可視 (invisible) and 光線 (light ray). The exact historical derivation is uncertain, but the term follows standard Sino-Japanese word formation patterns.