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[rent-guh n, -juh n, ruhnt-; for 1 also German rœnt-guh n] /ˈrɛnt gən, -dʒən, ˈrʌnt-; for 1 also German ˈrœnt gən/
Wilhelm Konrad
[wil-helm kon-rad;; German vil-helm kawn-raht] /ˈwɪl hɛlm ˈkɒn ræd;; German ˈvɪl hɛlm ˈkɔn rɑt/ (Show IPA),
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 Dictionary, © Random House, Inc. 2017.
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Examples from the Web for Roentgen
Historical Examples
  • The third are very penetrating rays, which are not deflected by electricity and which are seemingly identical with Roentgen rays.

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

    Unicorns James Huneker
  • Nothing could more vividly bear out this gentleman than contemplation of the possibilities of the Roentgen ray.

    Peeps at People Robert Cortes Holliday
  • We have seen the discovery of the Roentgen Rays born of observation.

    The Montessori Method Maria Montessori
  • It is with such a supply of electricity conducted through a vacuum tube that the cathode ray and the Roentgen ray are produced.

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

  • "That light wasn't exactly the Roentgen variety," Drake interrupted my absorption in our surroundings.

    The Metal Monster A. Merritt
  • Is it credible that old Melchizedek knew nothing about the telephone, or the Roentgen ray, or the cholera bacillus?

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

    The Treatment of Hay Fever George Frederick Laidlaw
  • At one time it was psychic force, then Roentgen or X-rays; lately it has been attributed to the mysterious effects of radium!

British Dictionary definitions for Roentgen


/ˈrɒntɡən; -tjən; ˈrɛnt-/
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 completely R, r
Word Origin
C20: named after W. K. Roentgen


/ˈrɒntɡən; -tjən; ˈrɛnt-; German ˈrœntɡən/
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
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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
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Roentgen in Medicine

roentgen roent·gen or rönt·gen (rěnt'gən, -jən, rŭnt'-)
Abbr. R, r
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.

Roentgen Roent·gen (rěnt'gən, -jən, rŭnt'-) or Rönt·gen (rɶnt'gən), 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.
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Roentgen in Science
  (rěnt'gən, rěnt'jən)   
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 © 2002. Published by Houghton Mifflin. All rights reserved.
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