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radiation

Pronunciation: /reɪdɪˈeɪʃ(ə)n/

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Definition of radiation

noun

[mass noun]
  • 1 Physics the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles which cause ionization.
  • the energy transmitted by radiation: background radiation [as modifier]:the radiation dose [count noun]:ultraviolet and infrared radiations
  • 2chiefly Biology divergence out from a central point, in particular evolution from an ancestral animal or plant group into a variety of new forms: evolution is a process of radiation not progression

Derivatives

radiational

adjective

radiationally

adverb

Origin:

late Middle English (denoting the action of sending out rays of light): from Latin radiatio(n-), from radiare 'emit rays' (see radiate)

radiation in other Oxford dictionaries

Definition of radiation in the US English dictionary

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