verb (used with object), i·on·ized, i·on·iz·ing.

to separate or change into ions.
to produce ions in.

verb (used without object), i·on·ized, i·on·iz·ing.

to become changed into the form of ions, as by dissolving.

Also especially British, i·on·ise.

Origin of ionize

First recorded in 1895–1900; ion + -ize
Related formsi·on·iz·a·ble, adjectivei·on·i·za·tion, nouni·on·iz·er, nounnon·i·on·ized, adjectivenon·i·on·iz·ing, adjectiveself-i·on·i·za·tion, nounun·i·o·nized, adjectiveun·un·ion·ized, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for ionize

Historical Examples of ionize

  • Organic compounds, on the other hand, ionize only very slowly, if at all.

    The Chemistry of Plant Life

    Roscoe Wilfred Thatcher

  • Second, the upper atmosphere of Eisberg was pretty much pure hydrogen, which is somewhat easier to ionize than oxygen or nitrogen.

    Unwise Child

    Gordon Randall Garrett

  • Certain ultra-violet rays also ionize the air and cause the formation of ozone.

    Artificial Light

    M. Luckiesh

British Dictionary definitions for ionize




to change or become changed into ions
Derived Formsionizable or ionisable, adjective
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 ionize

1896, from ion + -ize. Related: Ionized; ionizing.

Online Etymology Dictionary, © 2010 Douglas Harper

ionize in Medicine




To dissociate atoms or molecules into electrically charged atoms or radicals.
Related formsion•iz′er n.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

ionize in Science



To give an atom or group of atoms a net electric charge by adding or removing one or more electrons.
To form ions in a substance. Lightning ionizes air, for example.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.