or kat·i·on

[kat-ahy-uh n, -on]
noun Physical Chemistry.
  1. a positively charged ion that is attracted to the cathode in electrolysis.
  2. any positively charged atom or group of atoms (opposed to anion).

Origin of cation

1825–35; < Greek katión going down (neuter of katiṓn, present participle of kateînai), equivalent to kat- cat- + -i- go + -on neuter present participle suffix
Related formscat·i·on·ic [kat-ahy-on-ik] /ˌkæt aɪˈɒn ɪk/, adjectivecat·i·on·i·cal·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for cationic


  1. a positively charged ion; an ion that is attracted to the cathode during electrolysisCompare anion
Derived Formscationic (ˌkætaɪˈɒnɪk), adjective

Word Origin for cation

C19: from cata- + 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 cationic



1834, from Greek kation "going down," neuter present participle of katienai "to go down," from kata "down" (see cata-) + ienai "to go" (see ion). Proposed by the Rev. William Whewell (1794-1866), English polymath, and published by English physicist Michael Faraday.

Online Etymology Dictionary, © 2010 Douglas Harper

cationic in Medicine


  1. An ion or group of ions having a positive charge and characteristically moving toward the negative electrode in electrolysis.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

cationic in Science


  1. An ion with net positive charge, having more protons than electrons. In electrolysis, cations migrate to a negatively charged cathode. Compare anion.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.