ion

¹ American  

[ahy-uhn, ahy-on] / ˈaɪ ən, ˈaɪ ɒn /

noun

Physics, Chemistry.

1. an electrically charged atom or group of atoms formed by the loss or gain of one or more electrons, as a cation positive ion, which is created by electron loss and is attracted to the cathode in electrolysis, or as an anion negative ion, which is created by an electron gain and is attracted to the anode. The valence of an ion is equal to the number of electrons lost or gained and is indicated by a plus sign for cations and a minus sign for anions, thus: Na + , Cl−, Ca ++ , S = .

2. one of the electrically charged particles formed in a gas by electric discharge or the like.

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Ion ² American  

[ahy-on] / ˈaɪ ɒn /

noun

1. Classical Mythology. the eponymous ancestor of the Ionians: a son of Apollo and Creusa who is abandoned by his mother but returns to become an attendant in Apollo's temple at Delphi.

2. (italics) a drama on this subject (415? b.c.) by Euripides.

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-ion ³ American  

1. a suffix, appearing in words of Latin origin, denoting action or condition, used in Latin and in English to form nouns from stems of Latin adjectives (communion; union ), verbs (legion; opinion ), and especially past participles (allusion; creation; fusion; notion; torsion ).

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Ion. ⁴ American  

abbreviation

1. Ionic.

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-ion ¹ British  

suffix

1. indicating an action, process, or state Compare -ation -tion

   creation

   objection

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ion ² British  

/ ˈaɪən, -ɒn /

noun

1. an electrically charged atom or group of atoms formed by the loss or gain of one or more electrons See also cation anion

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ion Scientific  

/ ī′ən,ī′ŏn′ /

1. An atom or a group of atoms that has an electric charge. Positive ions, or cations, are formed by the loss of electrons; negative ions, or anions, are formed by the gain of electrons.

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ion Cultural  

1. An atom that has either lost or gained one or more electrons, so that it has an electrical charge. Ions can be either positively or negatively charged.

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Etymology

Origin of ion¹

< Greek ión going, neuter present participle of iénai to go; term introduced by Michael Faraday in 1834

Origin of -ion³

< Latin -iōn- (stem of -iō ) suffix forming nouns, especially on past participle stems; replacing Middle English -ioun < Anglo-French < Latin -iōn-

Example Sentences

The company designs and manufactures ion implantation equipment that is critical in creating transistors on chips.

From MarketWatch • Mar. 28, 2026

Still, Dorsheimer said the impending merger with Veeco “will complement Axcelis’s singular focus on ion implant and cast a wider net to cover semiconductor capital equipment.”

From MarketWatch • Mar. 28, 2026

Researchers eventually confirmed that TMEM175 is an ion channel that moves charged particles across the lysosomal membrane.

From Science Daily • Mar. 26, 2026

A version with 486 ports could hold up to ten billion charges at once, which is about a thousand times more than conventional ion traps.

From Science Daily • Mar. 25, 2026

The ion particles would fall out of phase, they said, or would crash into the walls of the accelerating chamber, or would collide with stray air molecules in their way.

From "Big Science" by Michael Hiltzik