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[an-ahy-uh n] /ˈænˌaɪ ən/
noun, Physical Chemistry.
a negatively charged ion, as one attracted to the anode in electrolysis.
any negatively charged atom or group of atoms (opposed to cation).
Origin of anion
1825-35; < Greek, neuter of aniṓn going up (present participle of aniénai to go up), equivalent to an- an-3 + -i- go + -ōn present participle suffix
Related forms
[an-ahy-on-ik] /ˌæn aɪˈɒn ɪk/ (Show IPA),
anionically, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for anion
Historical Examples
  • One of these is always composed of oxygen and hydrogen and is the anion.

  • Now, one question: Has the news of the death of the ram of anion reached you?

    Uarda, Complete Georg Ebers
  • The king repaired in state to the temple of anion, seized the priests who professed these seditious beliefs, and burnt them alive.

  • The Nile beyond surrounded an island, where flourished the well-kept sacred grove of anion.

    Uarda, Complete Georg Ebers
  • In a few minutes the priest of anion and the chief of the kolchytes were being carried towards the valley in their litters.

    Uarda, Complete Georg Ebers
  • In this the heart shall be preserved till a new ram offered by a worthy hand enters the herd of anion.

    Uarda, Complete Georg Ebers
  • It will be noticed that in neutralization the anion of the acid and the cation of the base are not changed.

British Dictionary definitions for anion


a negatively charged ion; an ion that is attracted to the anode during electrolysis Compare cation
Derived Forms
anionic (ˌænaɪˈɒnɪk) adjective
Word Origin
C19: from ana- + ion
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for anion

"a negatively charged ion, which moves toward the anode (q.v.) during electrolysis," 1834, proposed by the Rev. William Whewell (1794-1866), English polymath, and published by English physicist Michael Faraday, from Greek anion "(thing) going up," neuter past participle of anienai "go up," from ana "up" (see ana-) + ienai "go" (see ion).

Online Etymology Dictionary, © 2010 Douglas Harper
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anion in Medicine

anion an·i·on (ān'ī'ən)
A negatively charged ion, especially one that migrates to the anode in electrolysis.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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anion in Science
An ion with net negative charge, having more electrons than protons. In electrolysis, anions migrate to a positively charged anode. Compare cation.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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