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


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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 Hundreds of psychology experiments from the past 30 years have explored how people react to the thought of their own death. Jeff Greenberg, The Conversation, "Coronavirus reminds you of death – and amplifies your core values, both bad and good," 21 May 2020 Without thinking, Colavolpe smiled at her through the window, but was confused when the nurse didn’t react. Annie Vainshtein,, "A Bay Area without smiles: Coronavirus masks are taking away our most vital form of nonverbal communication," 21 May 2020 The changes are expected to be implemented immediately, as the NFL reacts to another hiring cycle in which minority candidates were largely shut out of being hired for coaching and executive positions. oregonlive, "NFL to implement major changes to the ’Rooney Rule’: Report," 19 May 2020 The immune system recognizes molecules on these pieces, called antigens, as threats and reacts by making antibodies, molecules that can find the virus anywhere in the body and neutralize it. Charles Schmidt, Scientific American, "Genetic Engineering Could Make a COVID-19 Vaccine in Months Rather Than Years," 29 Apr. 2020 Social media is in a frenzy as people react to the recent announcement by Gov. Greg Abbott to reopen Texas beginning May 1. Sonia Ramirez, Houston Chronicle, "Social media reacts to Gov. Gregg Abbott reopening Texas," 28 Apr. 2020 But this explanation misses one fact: the West didn't have to go through the same cycles as Asia, where governments and public health systems had little warning of the virus and scrambled to understand it while reacting to outbreaks. James Griffiths, CNN, "As coronavirus spread through Asia, the West had a head start to prepare. Why wasn't it used?," 16 Apr. 2020 As America reacts to one thing or another, each on its own, isolated terms, and often unsuccessfully, the underlying forces gathering to its disadvantage advance as if wholly unrecognized. Mark Helprin, National Review, "American Foreign and Defense Policy: Between Scylla and Charybdis," 16 Apr. 2020 As the world reacts to the COVID-19 pandemic, people across the planet are staying home, quarantining, and practicing social distancing as an effort to slow — and hopefully stop — the spread of coronavirus. Tanner Saunders, Travel + Leisure, "100+ Fun Things to Do at Home Right Now, From Virtual Tours to Animals Cams and More," 3 Apr. 2020

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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Time Traveler for react

Time Traveler

The first known use of react was in 1644

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Statistics for react

Last Updated

26 May 2020

Cite this Entry

“React.” Dictionary, Merriam-Webster, Accessed 3 Jun. 2020.

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More Definitions for react


How to pronounce react (audio)

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

Thesaurus: All synonyms and antonyms for react

Rhyming Dictionary: Words that rhyme with react

Spanish Central: Translation of react

Nglish: Translation of react for Spanish Speakers

Britannica English: Translation of react for Arabic Speakers

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