radiation

noun

ra·​di·​a·​tion ˌrā-dē-ˈā-shən How to pronounce radiation (audio)
1
a
: 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
2
a
: something that is radiated
b
: energy radiated in the form of waves or particles
3
: radial arrangement
4
radiational adjective
radiationless adjective
radiative adjective

Example Sentences

She was exposed to high levels of radiation. He goes in for radiation next week. the sun's radiation of heat
Recent Examples on the Web Air travelers would be exposed to more than a year’s worth of natural radiation levels in just a few seconds. Maren Estrada, BGR, 30 Nov. 2022 Many of the rocks have been shaped by the wind and may have experienced some chemical alterations due to the atmosphere or radiation exposure. John Timmer, Ars Technica, 23 Nov. 2022 Two other mannequin torsos will also travel aboard the flight, wearing vests designed to reduce radiation exposure. Micah Maidenberg, WSJ, 16 Nov. 2022 The spacecraft is carrying a set of mannequins laden with sensors to study conditions during the flight and to measure radiation levels throughout the mission. Denise Chow, NBC News, 16 Nov. 2022 Greece and Switzerland routinely monitor radio-frequency radiation levels throughout the country. Peter Elkind, ProPublica, 10 Nov. 2022 There has been a rush elsewhere in Europe on potassium iodide — which protects the thyroid gland in the neck in case of radiation exposure — including in Finland where the government urged the population to buy them. Vanessa Gera, Anchorage Daily News, 21 Oct. 2022 To be most effective, the pills must be taken within 24 hours before, or four hours after, radiation exposure. WIRED, 18 Oct. 2022 The use of potassium iodide (KI) is commonly associated with radiation exposure. Tim Newcomb, Popular Mechanics, 17 Oct. 2022 See More

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.

Word History

First Known Use

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

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

Dictionary Entries Near radiation

Cite this Entry

“Radiation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radiation. Accessed 4 Dec. 2022.

Kids Definition

radiation

noun

ra·​di·​a·​tion ˌrād-ē-ˈā-shən How to pronounce radiation (audio)
1
: the action or process of radiating
especially : the process of giving off radiant energy in the form of waves or particles
2
: something that is radiated
especially : energy radiated in the form of waves or particles
radiational
-shnəl How to pronounce radiation (audio)
-shən-ᵊl
adjective

Medical Definition

radiation

noun

ra·​di·​a·​tion ˌrād-ē-ˈā-shən How to pronounce radiation (audio)
1
: energy radiated in the form of waves or particles
2
a
: 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

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