radiation

noun
ra·​di·​a·​tion | \ ˌrā-dē-ˈā-shən How to pronounce radiation (audio) \

Definition of radiation

1a : the action or process of radiating
b : the process of emitting radiant energy in the form of waves or particles
c(1) : the combined processes of emission, transmission, and absorption of radiant energy
(2) : the transfer of heat by radiation — compare conduction, convection
2a : something that is radiated
b : energy radiated in the form of waves or particles
3 : radial arrangement

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Other Words from radiation

radiational \ ˌrā-​dē-​ˈā-​shnəl How to pronounce radiation (audio) , -​shə-​nᵊl \ adjective
radiationless \ ˌrā-​dē-​ˈā-​shən-​ləs How to pronounce radiation (audio) \ adjective
radiative \ ˈrā-​dē-​ˌā-​tiv How to pronounce radiation (audio) \ adjective

Examples of radiation in a Sentence

She was exposed to high levels of radiation. He goes in for radiation next week. the sun's radiation of heat
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Recent Examples on the Web Early on, for example, the Universe was mostly radiation: in the form of photons and neutrinos. Ethan Siegel, Forbes, 21 May 2021 The reason, according to Ukrainian prosecutors, wasn’t radiation, but problems with the bottles’ customs documents. Yulia Drozd, ABC News, 16 May 2021 The instrument has measured the radiation from two neutron stars 1.4 and 2.1 times as massive as the Sun and has found both to be about 13 kilometers in radius. Adrian Cho, Science | AAAS, 27 Apr. 2021 But the radiation from Chernobyl wasn’t enough to kill cells. Sara Harrison, Wired, 26 Apr. 2021 The isotope’s radioactive half life is 30 years, meaning the worst of the radiation from these specific test blasts is well behind us. Caroline Delbert, Popular Mechanics, 21 Apr. 2021 At the beginning of the outbreak, many WhatsApp users forwarded with dizzying speed allegations that COVID-19 was manufactured in a Chinese lab, or that radiation from 5G internet towers caused the disease. Ryan Lenora Brown, The Christian Science Monitor, 4 Mar. 2021 Scientists routinely monitor space weather because radiation from particles from the sun can wreak havoc on satellites in orbit and can occasionally disrupt infrastructure on the ground, such as surges in power lines. NBC News, 4 Mar. 2021 Two-thirds were given the radiation drug and the rest served as a comparison group. Carla K. Johnson, chicagotribune.com, 4 June 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'radiation.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of radiation

15th century, in the meaning defined at sense 1a

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Learn More About radiation

Time Traveler for radiation

Time Traveler

The first known use of radiation was in the 15th century

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Statistics for radiation

Last Updated

18 Jun 2021

Cite this Entry

“Radiation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radiation. Accessed 24 Jun. 2021.

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More Definitions for radiation

radiation

noun

English Language Learners Definition of radiation

: a type of dangerous and powerful energy that is produced by radioactive substances and nuclear reactions
medical : the use of controlled amounts of radiation for the treatment of diseases (such as cancer)
: energy that comes from a source in the form of waves or rays you cannot see

radiation

noun
ra·​di·​a·​tion | \ ˌrā-dē-ˈā-shən How to pronounce radiation (audio) \

Kids Definition of radiation

1 : the process of giving off energy in the form of waves or particles
2 : something that is radiated (as light or X-rays)

radiation

noun
ra·​di·​a·​tion | \ ˌrād-ē-ˈā-shən How to pronounce radiation (audio) \

Medical Definition of radiation

1 : energy radiated in the form of waves or particles
2a : the action or process of radiating with radiation of the pain there may be tenderness over the sciatic nerve— J. A. Key
b(1) : the process of emitting radiant energy in the form of waves or particles
(2) : the combined processes of emission, transmission, and absorption of radiant energy
3 : a tract of nerve fibers within the brain especially : one concerned with the distribution of impulses arising from sensory stimuli to the relevant coordinating centers and nuclei the optic radiations

More from Merriam-Webster on radiation

Nglish: Translation of radiation for Spanish Speakers

Britannica English: Translation of radiation for Arabic Speakers

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