radiation

noun ra·di·a·tion \ ˌrā-dē-ˈā-shən \
Updated on: 10 Dec 2017

Definition of radiation

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

radiational

play \ˌrā-dē-ˈā-shnəl, -shə-nᵊl\ adjective

radiationless

play \ˌrā-dē-ˈā-shən-ləs\ adjective

radiative

play \ˈrā-dē-ˌā-tiv\ adjective

Examples of radiation in a Sentence

  1. She was exposed to high levels of radiation.

  2. He goes in for radiation next week.

  3. the sun's radiation of heat

Recent Examples of radiation from the Web

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.

First Known Use of radiation

15th century


RADIATION Defined for English Language Learners

radiation

noun

Definition of radiation for English Language Learners

  • : 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 Defined for Kids

radiation

noun ra·di·a·tion \ ˌrā-dē-ˈā-shən \

Definition of radiation for Students

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

Medical Dictionary

radiation

noun ra·di·a·tion \ ˌrād-ē-ˈā-shən \

medical Definition of radiation

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


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