Etymology 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 chess sense is metaphorical, referring to control passing through a seemingly solid barrier.
1
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.
X-rays are light with a wavelength between 0.1 and 10 nm.
2
A radiograph: an image made with X-rays.
The doctor ordered some X-rays of my injured wrist.
And this friendly was not without its injury worries, with defender Gary Cahill substituted early on after a nasty, needless push by Dries Mertens that caused him to collide with goalkeeper Joe Hart, an incident that left the Chelsea defender requiring a precautionary X-ray at Wembley.2012 June 2, Phil McNulty, “England 1-0 Belgium”, in BBC Sport:
3
An X-ray machine, a machine for performing radiography.
4
Board games, Chess, Games A tactical motif where a piece exerts influence or control over a square, piece, or line indirectly through another intervening piece.
Etymology 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 chess sense is metaphorical, referring to control passing through a seemingly solid barrier.
1
Informal To take a radiograph of; to obtain an image of using X-ray radiation, especially for the purpose of medical diagnostic evaluation.
Of course there was nothing wrong with my left wrist. They X-rayed the wrong arm!
1925, Sidney Coe Howard, They Knew What They Wanted (Doubleday, Page and Company), Act II, page 116. Both legs broken in the morning. Tibia, fibula, femur, and ischium. X-rayed and set inside of an hour after the accident.
2
Board games, Chess, Games Of a piece, to exert indirect influence, by either attacking, defending, or controlling an opponent's or friendly piece through an intervening piece along a rank, file, or diagonal.
X-ray
adj
Etymology 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 chess sense is metaphorical, referring to control passing through a seemingly solid barrier.
1
Of or relating to X-rays.
I had to put my bags through an X-ray scanner at the airport.
Who will fly and have X-ray eyes— And be known as the man no bullet can kill?1974, Shel Silverstein, “Who”, in Where the Sidewalk Ends, HarperCollins: