ion

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noun \ˈī-ən, ˈī-ˌän\

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
2 : a charged subatomic particle (such as a free electron)

See ion defined for English-language learners

Recent Examples of ion from the Web

The cost of lithium ion batteries, the gold standard in solar power storage, has fallen significantly, Mr. Turner said, largely because of economies of scale.

— geeta anand, New York Times, "India, Once a Coal Goliath, Is Fast Turning Green", 2 June 2017
MARRAKECH, Morocco — Morocco’s government ion Thursday defended police actions in a northern town where arrests of demonstrators have aggravated public anger over corruption and poor economic conditions.

— Washington Post, "Moroccan government seeks calm after northern protests", 1 June 2017
Lapan said Tuesday's fire aboard a Jet Blue flight caused by a lithium-ion battery did not change the government's thinking about expanding the restriction on electronic devices.

— pete williams, NBC News, "Laptops Onboard Flights From U.S. Could Be Banned", 1 June 2017
Most rechargeable electronic devices, like laptops, are powered by lithium-ion batteries.

— CBS News, "JetBlue flight diverted after fire in passenger's electronic device", 31 May 2017
Last year, Samsung's Galaxy Note 7 phones were banned from all flights after the company discovered that its lithium-ion batteries were faulty and could overheat and catch fire.

— eric levenson and aaron cooper, CNN, "Flight diverted when laptop's lithium battery catches fire", 31 May 2017
The Pennsylvania and Indiana prison systems regularly use ion detection scanning –

— gavin off and ames alexander, charlotteobserver, "How NC prisons make life too easy for officers who smuggle drugs, cellphones", 31 May 2017
Nerve cells have tiny pores in their cell membranes that regulate the flow of sodium ions into the cell, which in turn modulates the firing of the cell.

— karen weintraub, Scientific American, "Revenge of the Super Lice", 29 May 2017
That means a lithium ion battery can run at a higher power for a longer time than a nickel metal battery of the same weight.

— matthew shechmeister, WIRED, "Driving Green, Explosion-Free", 26 Aug. 2005

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.

Origin and Etymology of ion

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

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First Known Use: circa 1834

See Words from the same year

Other Chemical Engineering Terms

alkali, cation, decant, hygroscopic, isotope, oxidize, slurry, solute, viscous

Ion

abbreviation

Definition of Ion

Ionic

-ion

noun suffix

Definition of -ion

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

Origin and Etymology of -ion

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

ION Defined for English Language Learners

ion

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noun

Definition of ion for English Language Learners

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

-ion

noun suffix

Definition of -ion for English Language Learners

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

ION Defined for Kids

ion

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noun \ˈī-ən, ˈī-ˌän\

Definition of ion for Students

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

-ion

noun suffix

Definition of -ion for Students

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

Medical Dictionary

ion

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noun \ˈī-ən, ˈī-ˌän\

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)