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
Returning to the team's analysis, an isotope is an atom of a specific element that has the same number of protons but a different number of neutrons — and Dottin wanted to check the isotopic ratios of sulfur, which a secondary ion mass spectrometry can measure precisely. Keith Cooper, Space.com, 13 Oct. 2025 Once captured by the QuBUS, the photons were coupled into a fiber optic cable and sent to an ion trap at the Max Planck Institute for the Science of Light (MPL) in Erlangen for analysis. Aman Tripathi, Interesting Engineering, 10 Oct. 2025 These external influences excite the molecules and atoms in the rings, creating ions. Big Think, 9 Oct. 2025 Susumu Kitagawa, Richard Robson, and Omar Yaghi discovered that copper ions could be used to create a crystal with large cavities within it, which was porous to smaller atoms and molecules but blocked larger ones. Tom Chivers, semafor.com, 8 Oct. 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 15 Oct. 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)

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