[rent-guh n, -juh n, ruhnt-; for 1 also German rœnt-guh n]


Wil·helm Kon·rad [wil-helm kon-rad; German vil-helm kawn-raht] /ˈwɪl hɛlm ˈkɒn ræd; German ˈvɪl hɛlm ˈkɔn rɑt/, 1845–1923, German physicist: discoverer of x-rays 1895; Nobel prize 1901.
(lowercase) Physics. a unit of exposure dose that measures x-rays or gamma rays in terms of the ions or electrons produced in dry air at 0° C and one atmosphere, equal to the amount of radiation producing one electrostatic unit of positive or negative charge per cubic centimeter of air. Abbreviation: r, R


(sometimes lowercase) of or relating to Wilhelm Roentgen, the Roentgen unit, or especially to x-rays.

Also Röntgen. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for roentgen

Historical Examples of roentgen

  • The morphine injection and the Roentgen rays are by far more dangerous.


    Hugo Mnsterberg

  • Call it the X-poison, if you will, as Roentgen did with his unknown ray.

    The Treatment of Hay Fever

    George Frederick Laidlaw

  • What miracles are wireless telegraphy, flying-machines, the Roentgen ray!


    James Huneker

  • We have seen the discovery of the Roentgen Rays born of observation.

    The Montessori Method

    Maria Montessori

  • Luckily, not even Roentgen rays could discover what a store of drawings, charts, and fortress plans I keep in my memory.

British Dictionary definitions for roentgen




a unit of dose of electromagnetic radiation equal to the dose that will produce in air a charge of 0.258 × 10 –3 coulomb on all ions of one sign, when all the electrons of both signs liberated in a volume of air of mass one kilogram are stopped completelySymbol: R, r

Word Origin for roentgen

C20: named after W. K. Roentgen




Wilhelm Konrad (ˈvɪlhɛlm ˈkɔnraːt). 1845–1923, German physicist, who in 1895 discovered X-rays: Nobel prize for physics 1901
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

Word Origin and History for roentgen

1896, in Roentgen rays "X-rays," in recognition of German physicist Wilhem Conrad Röntgen (1845-1923), who discovered X-rays in 1895. As a unit of exposure to radiation, it is attested from 1922, proposed in French in 1921.

Online Etymology Dictionary, © 2010 Douglas Harper

roentgen in Medicine



A unit of radiation exposure that is equal to the quantity of ionizing radiation that will produce one electrostatic unit of electricity in one cubic centimeter of dry air at 0°C and standard atmospheric pressure.


[rĕntgən, -jən, rŭnt-] Wilhelm Konrad 1845-1923

German physicist who discovered x-rays and developed x-ray photography, revolutionizing medical diagnosis. He won a 1901 Nobel Prize.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

roentgen in Science


[rĕntgən, rĕntjən]Wilhelm Konrad 1845-1923

German physicist who discovered x-rays in 1895 and went on to develop x-ray photography, which revolutionized medical diagnosis. In 1901 he was awarded the Nobel Prize for physics.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.