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)

Ion

2 of 3

abbreviation

Ionic

-ion

3 of 3

noun suffix

1
a
: 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Noun
Its Organic SolidFlow technology is designed for long-duration storage, targeting commercial and utility-scale customers who need performance beyond what lithium-ion typically offers. Anna Broughel, Forbes.com, 9 Sep. 2025 At the same time, its broader technology pipeline, spanning sodium-ion chemistries, dual-power pack designs, integrated chassis, and tougher safety credentials, signals the company’s intent to compete across performance, cost, and reliability in one of the world’s most demanding EV markets. Kaif Shaikh, Interesting Engineering, 8 Sep. 2025 That's due to polarization, which hampers the movement of lithium ions into the battery's electrodes during rapid charging and discharging. Abhimanyu Ghoshal, New Atlas, 6 Sep. 2025 In general, those with lithium-ion or lithium-metal batteries should also be carried on board, where flight crews can recognize and respond to lithium battery fires, according to the FAA. Eve Chen, USA Today, 5 Sep. 2025 See All Example Sentences for ion

Word History

Etymology

Noun

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

Noun suffix

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

First Known Use

Noun

circa 1834, in the meaning defined at sense 1

Time Traveler
The first known use of ion was circa 1834

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Cite this Entry

“Ion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ion. Accessed 10 Sep. 2025.

Kids Definition

ion

1 of 2 noun
ˈī-ən How to pronounce ion (audio)
ˈī-ˌän
: 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

-ion

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

Noun suffix

derived from Latin -ion (suffix) "act or process"

Medical Definition

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)

More from Merriam-Webster on ion

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