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

Being in space means being exposed to radiation, so stations need additional shielding to protect inhabitants. Joe Pappalardo, Popular Mechanics, "Maybe NASA's Next Space Station Doesn't Need the Astronauts," 6 Sep. 2018 And of course, the extended exposure to radiation can lead to all sorts of problems, including cancer. Alex Stuckey, Houston Chronicle, "Research shows lungs heal more slowly in space, a problem NASA must fix before trip to Mars," 1 Mar. 2018 An additional proposal would require that as SPF increases, the amount of protection against UVA radiation also increases. Caroline Picard, Good Housekeeping, "What the New Proposed FDA Sunscreen Regulations Mean for You," 22 Feb. 2019 Imagine if it had been employed to alert the media to the dubious, longstanding, likely fraudulent science of radiation risk that has so inhibited the development of nuclear power. Holman W. Jenkins, WSJ, "Big Names Bake a Climate Pie in the Sky," 18 Jan. 2019 Each one has its own unique task, such as studying the radiation belts around Earth or demonstrating new ways to propel vehicles through space. Loren Grush, The Verge, "Small satellite launcher Rocket Lab is poised to send up its first batch of spacecraft for NASA," 12 Dec. 2018 Come for the radiation side effects, stay for the breakdown of US-North Korea relations. Byrd Pinkerton, Vox, "13 of Vox’s best podcast episodes of 2018," 6 Dec. 2018 Then, all the electrons start emitting lots of energy as radiation. Chris Lee, Ars Technica, "Single-beam laser becomes multi-beam laser by kicking electrons," 5 Dec. 2018 Because Venus’s upper atmosphere has similar pressure, density, gravity, and radiation protection to Earth’s surface, NASA is considering an airship-style vehicle for exploring the planet. Fox News, "NASA eyes stunning 'cloud city' airship concept to explore Venus," 16 Oct. 2018

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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Last Updated

12 Mar 2019

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Time Traveler for radiation

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

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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

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More from Merriam-Webster on radiation

Rhyming Dictionary: Words that rhyme with radiation

Spanish Central: Translation of radiation

Nglish: Translation of radiation for Spanish Speakers

Britannica English: Translation of radiation for Arabic Speakers

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