English
X-ray
From X + ray, a calque of German X-Strahl, coined by Wilhelm Röntgen upon his discovery of the rays in 1895, where X signifies their unknown nature.
The story
From X + ray, a calque of German X-Strahl, coined by Wilhelm Röntgen upon his discovery of the rays in 1895, where X signifies their unknown nature.uncertain The source flags this step as uncertain. The chess sense is metaphorical, referring to control passing through a seemingly solid barrier.
Today it means
noun A ray of short-wavelength electromagnetic radiation usually produced by bombarding a metal target in a vacuum. Used to create images of the internal structure of objects; this is possible because X-rays pass through most objects and can expose photographic film.
Language periods are conventional ranges, not dates for this word.
Etymograph / X-ray