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extinction

 - 7 dictionary results

ex·tinc·tion

   [ik-stingk-shuhn]
–noun
1.
the act of extinguishing.
2.
the fact or condition of being extinguished or extinct.
3.
suppression; abolition; annihilation: the extinction of an army.
4.
Biology. the act or process of becoming extinct; a coming to an end or dying out: the extinction of a species.
5.
Psychology. the reduction or loss of a conditioned response as a result of the absence or withdrawal of reinforcement.
6.
Astronomy. the diminution in the intensity of starlight caused by absorption as it passes through the earth's atmosphere or through interstellar dust.
7.
Crystallography, Optics. the darkness that results from rotation of a thin section to an angle (extinction angle) at which plane-polarized light is absorbed by the polarizer.
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Origin:
1375–1425; late ME extinccio(u)n < L ex(s)tinctiōn- (s. of ex(s)tinctiō). See extinct, -ion

—Related forms
non·ex·tinc·tion, noun
pre·ex·tinc·tion, noun
self-ex·tinc·tion, noun
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2010.
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Word Origin & History

extinction
late 15c., from L. extinctionem/exstinctionem, noun of action from extinguere/exstinguere (see extinguish). Originally of fires, lights; figurative use, of wiping out a material thing (a debt, a person, a family, etc.) from early 17c.; of species from 1880.
Online Etymology Dictionary, © 2010 Douglas Harper
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ex·tinc·tion   (ĭk-stĭngk'shən)   
n.  

    1. The act of extinguishing.

    2. The condition of being extinguished.

  2. The fact of being extinct or the process of becoming extinct: "The most effective agent in the extinction of species is the pressure of other species" (Alfred R. Wallace).

  3. Psychology A reduction or a loss in the strength or rate of a conditioned response when the unconditioned stimulus or reinforcement is withheld.

  4. Physiology A gradual decrease in the excitability of a nerve to a previously adequate stimulus, usually resulting in total loss of excitability.

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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Medical Dictionary

Main Entry: ex·tinc·tion
Pronunciation: ik-'sti[ng](k)-sh&n
Function: noun
1 : the process of becoming extinct extinction of a species>; also : the condition or fact of being extinct
2 : the process of eliminating or reducing a conditioned response by notreinforcing it
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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extinction ex·tinc·tion (ĭk-stĭngk'shən)
n.
Progressive reduction in the strength of the conditioned response in successive conditioning trials during which only the conditioned stimulus is presented and the unconditioned stimulus is omitted. See absorbance.

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
extinction   (ĭk-stĭngk'shən)  Pronunciation Key 

  1. The fact of being extinct or the process of becoming extinct. See more at background extinction, mass extinction.

  2. A progressive decrease in the strength of a conditioned response, often resulting in its elimination, because of withdrawal of a specific stimulus.


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

extinction

The disappearance of a species from the Earth.

Note: The fossil record tells us that 99.9 percent of all species that ever lived are now extinct.
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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