[ an-ahy-uhn ]
/ ˈænˌaɪ ən /
Save This Word!

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).



Apostrophes can be tricky; prove you know the difference between it’s and its in this crafty quiz!
Question 1 of 12
On the farm, the feed for chicks is significantly different from the roosters’; ______ not even comparable.

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
an·i·on·ic [an-ahy-on-ik], /ˌæn aɪˈɒn ɪk/, adjectivean·i·on·i·cal·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

British Dictionary definitions for anion

/ (ˈænˌaɪən) /


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

Medical definitions for anion

[ ănī′ən ]


A negatively charged ion, especially one that migrates to the anode in electrolysis.
ani•onic (-ŏnĭk) adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for anion

[ ănī′ən ]

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.
What's This Word?