interaction

American  

[in-ter-ak-shuhn] / ˌɪn tərˈæk ʃən /

noun

• interactions
  plural

1. 

   reciprocal action, effect, or influence.

2. Physics.

   1. the direct effect that one kind of particle has on another, in particular, in inducing the emission or absorption of one particle by another.

   2. the mathematical expression that specifies the nature and strength of this effect.

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interaction British  

/ ˌɪntərˈækʃən /

noun

1. a mutual or reciprocal action or influence

2. physics the transfer of energy between elementary particles, between a particle and a field, or between fields See strong interaction electromagnetic interaction fundamental interaction gravitational interaction weak interaction electroweak interaction

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Other Word Forms

Derived Forms

• interactional
  adjective

Inflected Forms

Nouns

• interactions
  plural

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Etymology

Origin of interaction

First recorded in 1825–35; inter- + action

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Explanation

If you interact with someone — by talking, looking, sharing, or engaging in any kind of action that involves the two of you — you can be said to have had an interaction with that person. Interaction comes from Latin inter meaning "between," and ago meaning "to do" or "to act" — any “action between” is considered an interaction, like the interaction between a teacher and a student, two countries, or even baking soda and vinegar (boom!).

Example Sentences

See Examples For:

interaction interactions

“Having said that, the interaction is no longer that outwardly,” he added.

From The Wall Street Journal ● Oct. 17, 2026

“We just say, ‘I’ve formed my position and I’m locked into it’ and we don’t share enough interaction where we can discuss things.

From Los Angeles Times ● Oct. 16, 2026

"A specifically designed coating could, in the future, facilitate this transfer and the interaction between mitochondria and cells," emphasizes Dr. Tiranti.

From Science Daily ● Oct. 13, 2026

Lactose intolerance is also often confused with disorders of the gut-brain interaction, says Shaukat.

From The Wall Street Journal ● Oct. 12, 2026

Based in southern Ohio, the Hopewell interaction sphere lasted until about 400 a.d. and extended across two-thirds of what is now the United States.

From "1491" by Charles C. Mann

Repeated across millions of interactions, modest savings could become meaningful.

From MarketWatch ● Oct. 16, 2026

Democracy requires interactions, and if we cannot find a way to find common ground, that’s my big worry.”

From Los Angeles Times ● Oct. 16, 2026

His interactions with Holmes are pure cringe comedy, like when she starts to cry perhaps a bit on cue and he stiffly sputters, “Do you want, like, a tissue?”

From Los Angeles Times ● Oct. 14, 2026

The Southport Inquiry began formally on 7 April 2025 to examine the overall timeline of the killer's history and interactions with various public bodies.

From BBC ● Oct. 12, 2026

If you transcribed that person’s interactions with his clients, he would sound just like Tom Gau because he would be using all of Tom Gau’s words.

From "The Tipping Point" by Malcolm Gladwell

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Related Words

• communication
• cooperation
• synergy

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