ion

noun
\ ˈī-ən How to pronounce ion (audio) , ˈī-ˌän\

Definition of ion

 (Entry 1 of 3)

1 : an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons
2 : a charged subatomic particle (such as a free electron)

Definition of Ion (Entry 2 of 3)

Ionic

Definition of -ion (Entry 3 of 3)

1a : act or process validation
b : result of an act or process regulation
2 : state or condition hydration

Examples of ion in a Sentence

Recent Examples on the Web: Noun

Lithium ion is still considered to be one of the lightest and most efficient battery solutions. Lauren Goode, WIRED, "Batteries Still Suck, But Researchers Are Working on It," 22 May 2018 These liquids enable ions to flow between electrodes separated by a porous membrane, thus creating a current. Matthew Sedacca, Scientific American, "These New Batteries Won't Make Your Smartphone Explode," 1 Oct. 2017 In this case, the electric field controlled the presence of lithium ions in the spaces in between layers of the MoS2. John Timmer, Ars Technica, "Researchers make RAM from a phase change we don’t entirely understand," 18 Dec. 2018 Lithium ions move from one side to the other, helped by highly flammable chemicals in the middle called electrolytes. Angela Chen, The Verge, "The best solution for making batteries safer might be the most boring one," 13 Aug. 2018 As in a battery being charged, charged ions flow between two electrodes supplied with electricity. Robert F. Service, Science | AAAS, "Ammonia—a renewable fuel made from sun, air, and water—could power the globe without carbon," 12 July 2018 The researchers think that these ions may have started out in the hearts of stars that went supernova, then were thrown out of their home galaxies by these explosive stellar deaths. Amina Khan, latimes.com, "After years of searching, scientists can finally account for all the normal matter in the universe," 20 June 2018 Some polymers can conduct ions, but that usually only works at extremely high temperatures. Angela Chen, The Verge, "The best solution for making batteries safer might be the most boring one," 13 Aug. 2018 When a battery is fully charged, the anode has sucked up lithium ions like a sponge. Christopher Mims, WSJ, "The Battery Boost We’ve Been Waiting for Is Only a Few Years Out," 18 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ion.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of ion

Noun

circa 1834, in the meaning defined at sense 1

History and Etymology for ion

Noun

Greek, neuter of iōn, present participle of ienai to go — more at issue entry 1

Noun suffix

French -ion, from Latin -ion-, -io

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Dictionary Entries near ion

Io moth

-ion

Ion

ion

Iona

ion chamber

ion channel

Statistics for ion

Last Updated

4 May 2019

Look-up Popularity

Time Traveler for ion

The first known use of ion was circa 1834

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More Definitions for ion

ion

noun

English Language Learners Definition of ion

 (Entry 1 of 2)

technical : an atom or group of atoms that has a positive or negative electric charge from losing or gaining one or more electrons

English Language Learners Definition of -ion (Entry 2 of 2)

: act or process
: result of an act or process
: state or condition

ion

noun
\ ˈī-ən How to pronounce ion (audio) , ˈī-ˌän\

Kids Definition of ion

: an atom or group of atoms that carries an electric charge

Kids Definition of -ion

1 : act or process construction
2 : result of an act or process regulation eruption
3 : state or condition perfection

ion

noun
\ ˈī-ən How to pronounce ion (audio) , ˈī-ˌän How to pronounce ion (audio) \

Medical Definition of ion

1 : an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons — see anion, cation
2 : a charged subatomic particle (as a free electron)

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More from Merriam-Webster on ion

Rhyming Dictionary: Words that rhyme with ion

Spanish Central: Translation of ion

Nglish: Translation of ion for Spanish Speakers

Britannica English: Translation of ion for Arabic Speakers

Britannica.com: Encyclopedia article about ion

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