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8 dictionary results for: Radiation
Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This
ra·di·a·tion       [rey-dee-ey-shuhn] Pronunciation Key
–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]

—Related forms
ra·di·a·tion·al, adjective
Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.
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American Heritage Dictionary - Cite This Source - Share This
ra·di·a·tion       (rā'dē-ā'shən)  Pronunciation Key 
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.
  4. 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.
(Download Now or Buy the Book)
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2006 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Online Etymology Dictionary - Cite This Source - Share This
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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WordNet - Cite This Source - Share This
radiation

noun
1. energy that is radiated or transmitted in the form of rays or waves or particles 
2. the act of spreading outward from a central source 
3. syndrome resulting from exposure to ionizing radiation (e.g., exposure to radioactive chemicals or to nuclear explosions); low doses cause diarrhea and nausea and vomiting and sometimes loss of hair; greater exposure can cause sterility and cataracts and some forms of cancer and other diseases; severe exposure can cause death within hours; "he was suffering from radiation" [syn: radiation sickness] 
4. the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay 
5. the spread of a group of organisms into new habitats 
6. a radial arrangement of nerve fibers connecting different parts of the brain 
7. (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance [syn: radiotherapy] 

WordNet® 3.0, © 2006 by Princeton University.
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The American Heritage Science Dictionary - Cite This Source - Share This
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.
  2. The use of such energy, especially x-rays, in medical diagnosis and treatment.

The American Heritage® Science Dictionary
Copyright © 2002 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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American Heritage New Dictionary of Cultural Literacy, Third Edition - Cite This Source - Share This
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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American Heritage Stedman's Medical Dictionary - Cite This Source - Share This

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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Webster's Revised Unabridged Dictionary - Cite This Source - Share This

Radiation

Ra`di*a"tion\, n. [L. radiatio: cf. F. radiation.]

1. The act of radiating, or the state of being radiated; emission and diffusion of rays of light; beamy brightness.

2. The shooting forth of anything from a point or surface, like the diverging rays of light; as, the radiation of heat.

Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc.
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