re·​act | \ rē-ˈakt How to pronounce react (audio) \
reacted; reacting; reacts

Definition of react

intransitive verb

1 : to exert a reciprocal or counteracting force or influence often used with on or upon
2 : to change in response to a stimulus
3 : to act in opposition to a force or influence usually used with against
4 : to move or tend in a reverse direction
5 : to undergo chemical reaction

transitive verb

: to cause to react

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Synonyms for react


reply, respond

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Examples of react in a Sentence

When I told her what happened, she reacted with anger. I didn't expect him to react that way. The firefighters reacted quickly when they heard the alarm. He reacted badly to the drug.
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Recent Examples on the Web

See how Daniel reacts when his former adversary gets there. Dalton Ross,, "Watch the Strand and Salazar reunion on Fear the Walking Dead," 7 June 2019 Erin Allday reports on how UCSF and scientists across the country are reacting. Taylor Kate Brown,, "Bay Briefing: Trump move ends HIV research partnership at UCSF," 6 June 2019 As early as the 1930s, scientists discovered that cells and tissue from human fetuses and embryos could be useful for medical studies—to test new drugs or to understand how human tissue might react to certain stimuli, for example. Amanda Macmillan,, "Fetal Tissue Research Facts and Why It's so Controversial," 6 June 2019 Here’s how officials in some of the other places have reacted. Chris Palmer,, "Facebook posts by cops: How other locations in database with Philly are reacting," 5 June 2019 Every person reacts differently and tolerance for discomfort may vary. Audrey Noble, Harper's BAZAAR, "Everything You Need To Know Before Getting A Brazilian Wax," 21 May 2019 Drogon, the only remaining dragon on the series, reacts to the incident in a surprising way. Katherine J. Igoe, Marie Claire, "Why Didn't Drogon Kill Jon Snow for Killing Daenerys in 'Game of Thrones'?," 20 May 2019 Saturday Night Live' star reacts to Chevy Chase's negative comments about the show. Fox News, "FOX NEWS FIRST: New allegations against Kavanaugh throw confirmation battle into chaos; Trump preps to address U.N.," 24 Sep. 2018 The market reacts Sempra stock finished the trading day at $115.11, down 85 cents or 0.73 percent. Rob Nikolewski,, "Sempra selling some of its assets — but activist investors appear unmoved," 28 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'react.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of react

1644, in the meaning defined at intransitive sense 1

History and Etymology for react

New Latin reactus, past participle of reagere, from Latin re- + agere to act — more at agent

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Statistics for react

Last Updated

10 Jun 2019

Look-up Popularity

Time Traveler for react

The first known use of react was in 1644

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More Definitions for react



English Language Learners Definition of react

: to behave or change in a particular way when something happens, is said, etc.
of a chemical substance : to change after coming into contact with another substance
medical : to be affected by a drug, food, etc., in usually a bad way


re·​act | \ rē-ˈakt How to pronounce react (audio) \
reacted; reacting

Kids Definition of react

1 : to act or behave in response to something Firefighters reacted quickly to the situation.
2 : to oppose a force or influence
Hint: In this sense, react is usually used with against. Workers reacted against unfair treatment.
3 : to go through a chemical reaction Acids react with bases to form salt.
re·​act | \ rē-ˈakt How to pronounce react (audio) \

Medical Definition of react

1 : to respond to a stimulus
2 : to undergo chemical reaction

transitive verb

: to cause to react

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More from Merriam-Webster on react

Rhyming Dictionary: Words that rhyme with react

Thesaurus: All synonyms and antonyms for react

Spanish Central: Translation of react

Nglish: Translation of react for Spanish Speakers

Britannica English: Translation of react for Arabic Speakers

Comments on react

What made you want to look up react? Please tell us where you read or heard it (including the quote, if possible).


incapable of being surmounted or overcome

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