or X-ray

[ eks-rey ]
See synonyms for x-ray on Thesaurus.com
nounAlso x ray, X ray.
  1. Physics.

    • Often x-rays. a form of electromagnetic radiation, similar to light but of shorter wavelength and capable of penetrating solids and of ionizing gases.

    • such radiation having wavelengths in the range of approximately 0.1–10 nanometers.

  2. a radiograph made by x-rays.

  1. (initial capital letter) a word in communications to represent the letter X.

verb (used with object)
  1. to examine, photograph, or treat with x-rays.

  1. of or relating to x-rays: x-ray examination of the digestive tract.

  2. able to see through objects that are opaque:the x-ray vision of Superman and other superheroes.

  1. able to clearly and keenly perceive or recognize something that is not outwardly visible: a teacher with x-ray intuition about her students.

Origin of x-ray

First recorded in 1895–1900; translation of German X-Strahl (1895), the name originally given to the rays by Röntgen, their discoverer, x signifying their unknown nature

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

British Dictionary definitions for X-ray


    • electromagnetic radiation emitted when matter is bombarded with fast electrons. X-rays have wavelengths shorter than that of ultraviolet radiation, that is less than about 1 × 10 –8 metres. They extend to indefinitely short wavelengths, but below about 1 × 10 –11 metres they are often called gamma radiation

    • (as modifier): X-ray astronomy

  1. a picture produced by exposing photographic film to X-rays: used in medicine as a diagnostic aid as parts of the body, such as bones, absorb X-rays and so appear as opaque areas on the picture

  1. (usually capital) communications a code word for the letter x

  1. to photograph (part of the body, etc) using X-rays

  2. to treat or examine by means of X-rays

Origin of X-ray

C19: partial translation of German X-Strahlen (from Strahl ray), coined by W. K. Roentgen in 1895

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for x-ray


  1. A high-energy stream of electromagnetic radiation having a frequency higher than that of ultraviolet light but less than that of a gamma ray (in the range of approximately 1016 to 1019 hertz). X-rays are absorbed by many forms of matter, including body tissues, and are used in medicine and industry to produce images of internal structures. See more at electromagnetic spectrum.

  2. An image of an internal structure, such as a body part, taken with x-rays.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for x-ray (1 of 2)


Notes for x-ray

Because x-rays can travel through solid material and affect photographic plates, they are widely used in diagnosing medical problems.

Notes for x-ray

Objects in the sky also send out x-rays in processes that use very high energy.

A photograph or image obtained through the use of x-rays. An x-ray is taken when an image of internal body structures (such as bones or organs) is needed to diagnose disease or determine the extent of injuries.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.