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

Etymology

Origin of interaction

First recorded in 1825–35; inter- + action

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

This lack of interaction means less chance for customers to show their gratitude in a country where tipping is widespread on everything from food delivery to haircuts.

From Barron's ● Aug. 29, 2026

Eitan, a 24-year-old chef and content creator, said using AI with voice interaction helps him bring down his screen time.

From The Wall Street Journal ● Aug. 27, 2026

It ushered in a new kind of fun that was fresher, busier and airier than past listservs and chatrooms, the dank basements of internet interaction.

From Salon ● Aug. 23, 2026

Under these conditions, the interaction between light and sound becomes more than 1000 times stronger than it is in standard optical fibers.

From Science Daily ● Aug. 22, 2026

Initial results showed a few key raised “islands” in control of a vast network of communication and interaction covering 200 square miles, as large as many early states.

From "1491" by Charles C. Mann

Their relationship will be closely monitored, along with further interactions between the central bank and executive branch, which has already faced much scrutiny.

From The Wall Street Journal ● Aug. 28, 2026

Dr Jessica Eccles, a researcher on brain-body interactions and hypermobility, says diagnosis can be a "postcode lottery in terms of where you are and what opportunities are available to you for assessment".

From BBC ● Aug. 27, 2026

His fan base is building quickly because he takes on relatable everyday occurrences, frustrations and interactions.

From Los Angeles Times ● Aug. 26, 2026

In this view, behavior emerges through ongoing interactions among the brain, body, and environment.

From Science Daily ● Aug. 25, 2026

Yet many of these localized functions are also controlled by interactions with other parts of the brain.

From "Phineas Gage" by John Fleischman

Related Words

• communication
• cooperation
• synergy