Borrowed from Latin radiatio, radiationis. By surface analysis, radiate +‎ -ion.

• (UK, US, Canada) IPA^(key): /ˌɹeɪ.diˈeɪ.ʃən/

  • Audio (London):

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  • Audio (Southern England):

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  • Audio (Texas):

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• (General Australian) IPA^(key): /ˌɹæɪ.diˈæɪ.ʃən/
• (some Ghanaian speakers) IPA^(key): /ɹæ.diˈeɪ.ʃən/

radiation (countable and uncountable, plural radiations)

1. The shooting forth of anything from a point or surface, like diverging rays of light.

   The radiation of love from the crowd was addictive to the young singer-songwriters.

   1. (often) Ellipsis of electromagnetic radiation.

      Synonym: EMR

      Hyponyms: alpha radiation, beta radiation, gamma radiation, X-radiation

      heat radiation

2. The process of radiating waves or particles.
3. The transfer of energy via radiation.

   Coordinate terms: convection, conduction

4. Radioactive energy.
   • 1986, "Weird Al" Yankovic, “Christmas at Ground Zero”, in Polka Party!‎^[1]:

     It's Christmas at ground zero / And if the radiation level's OK / I'll go out with you / To see all the new / Mutations on New Year's Day

5. (evolutionary theory, countable) A rapid diversification of an ancestral species into many new forms.
   • 2014, Elizabeth Kolbert, chapter 8, in The Sixth Extinction: An Unnatural History, Henry Holt and Company:

     So the question is: have plants and animals retained over this huge amount of time—whole radiations of mammals have come and gone in this period—have they retained these potentially costly characteristics?

   • 2016, Donald R. Prothero, The Princeton Field Guide to Prehistoric Mammals, page 136:

     The second [canid group] is the radiation of dogs in South America that began when the first canids arrived about 3 Ma, after crossing the Panama land bridge (Fig. 5.4).

• radiate
• radiative

• nucleomitophobia

• antiradio

Borrowed from Latin radiātiōnem.

• IPA^(key): /ʁa.dja.sjɔ̃/

• Audio (France (Lyon)):

  (file)

radiation f (plural radiations)

1. radiation (all meanings)

• ceinture de radiations de Van Allen

• radier

• → Romanian: radiație
• → Turkish: radyasyon

• “radiation”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012