# X-ray

> English word · Noun · IPA /ˈɛks ɹeɪ/

## Definitions
1. 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.
2. A radiograph: a photograph made with X-rays.
3. An X-ray machine.
4. 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.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/x-ray