[an-ahy-uh n]

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).

Nearby words

  1. animis opibusque parati,
  2. animism,
  3. animosity,
  4. animus,
  5. animé,
  6. anion exchange,
  7. anion gap,
  8. anion-exchange resin,
  9. anionic,
  10. anionic detergent

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 formsan·i·on·ic [an-ahy-on-ik] /ˌæn aɪˈɒn ɪk/, adjectivean·i·on·i·cal·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for anion

British Dictionary definitions for anion



a negatively charged ion; an ion that is attracted to the anode during electrolysisCompare cation
Derived Formsanionic (ˌænaɪˈɒnɪk), adjective

Word Origin for anion

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

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

Medicine definitions for anion




A negatively charged ion, especially one that migrates to the anode in electrolysis.
Related formsani•onic (-ŏnĭk) adj.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for anion



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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.