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radiation

 - 7 dictionary results

ra⋅di⋅a⋅tion

[rey-dee-ey-shuhn]
–noun
1. Physics.
a. the process in which energy is emitted as particles or waves.
b. the complete process in which energy is emitted by one body, transmitted through an intervening medium or space, and absorbed by another body.
c. the energy transferred by these processes.
2. the act or process of radiating.
3. something that is radiated.
4. radial arrangement of parts.

Origin:
1545–55; < L radiātiōn- (s. of radiātiō) a glittering, shining. See radiate, -ion


ra⋅di⋅a⋅tion⋅al, adjective
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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ra·di·a·tion   (rā'dē-ā'shən)   
n.  
  1. The act or process of radiating: the radiation of heat and light from a fire.

  2. Physics

    1. Emission and propagation and emission of energy in the form of rays or waves.

    2. Energy radiated or transmitted as rays, waves, in the form of particles.

    3. A stream of particles or electromagnetic waves emitted by the atoms and molecules of a radioactive substance as a result of nuclear decay.

    4. The act of exposing or the condition of being exposed to such energy.

    5. The application of such energy, as in medical treatment.

    6. The spread of a group of organisms into new habitats.

    7. Adaptive radiation.

    1. The act of exposing or the condition of being exposed to such energy.

    2. The application of such energy, as in medical treatment.

    3. The spread of a group of organisms into new habitats.

    4. Adaptive radiation.

  3. Anatomy Radial arrangement of parts, as of a group of nerve fibers connecting different areas of the brain.

    1. The spread of a group of organisms into new habitats.

    2. Adaptive radiation.

ra'di·a'tion·al, ra'di·a'tive adj.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Cultural Dictionary

radiation

Energy sent out in the form of particles or waves. (See alpha radiation, beta radiation, blackbody, cosmic rays, electromagnetic radiation, fluorescence, gamma radiation, photon, and quanta.)

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Word Origin & History

radiation 
1555, from L. radiationem (nom. radiatio) "a shining, radiation," noun of action from radiare "to beam, shine," from radius "beam of light" (see radius).
Online Etymology Dictionary, © 2001 Douglas Harper
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Medical Dictionary

Main Entry: ra·di·a·tion
Pronunciation: "rAd-E-'A-sh&n
Function: noun
1 : energy radiated in the form of waves or particles
2 a : the action or process of radiating radiation of the pain there may be tenderness over the sciatic nerve —J. A. Key> b (1) : theprocess 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 tractof nerve fibers within the brain; especially : one concerned with the distribution of impulses arising from sensory stimuli to the relevant coordinating centers and nuclei radiations>
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Medical Dictionary

radiation ra·di·a·tion (rā'dē-ā'shən)
n.

  1. The act or condition of diverging in all directions from a center.

  2. The emission and propagation of energy in the form of rays or waves.

  3. The energy radiated or transmitted in the form of rays, waves, or particles.

  4. A stream of particles or electromagnetic waves that is emitted by the atoms and molecules of a radioactive substance as a result of nuclear decay.

  5. Radiotherapy.

  6. The radial arrangement of anatomical or histological parts.

  7. The spread of a group of organisms into new habitats.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Science Dictionary
radiation   (rā'dē-ā'shən)  Pronunciation Key 
    1. Streams of photons, electrons, small nuclei, or other particles. Radiation is given off by a wide variety of processes, such as thermal activity, nuclear reactions (as in fission), and by radioactive decay.

    2. The emission or movement of such particles through space or a medium, such as air. See Notes at conduction, electromagnetic radiation.

  1. The use of such energy, especially x-rays, in medical diagnosis and treatment.


The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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