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 Governments around the world are reacting in varying degrees to the crisis. Jeremy Engle, New York Times, "What Questions Do You Have About the Coronavirus?," 27 Mar. 2020 Her husband of 14 years and former motorcycle racer, Carey Hart, reacted to her new hairdo with a simple emoji. Selena Barrientos, Good Housekeeping, "Pink’s Husband Carey Hart Had a Priceless Reaction After Seeing the Singer's DIY Haircut," 27 Mar. 2020 The markets reacted to the House hurrying to approve the coronavirus relief package that has already passed the Senate. Jay Heflin, Washington Examiner, "Best three-day rally since Great Depression in jeopardy as stocks fall," 27 Mar. 2020 People in these product launches react with a sort of feverish enthusiasm. Adam Epstein, Quartz, "In “Devs,” creator Alex Garland sees Silicon Valley for what it really is," 27 Mar. 2020 Coronavirus impact: After one-day gain, how will markets react? Editors, USA TODAY, "Coronavirus outbreak, stimulus package, India lockdown: 5 things to know Wednesday," 26 Mar. 2020 Olympians Emma Coburn and Jenny Simpson react to the decision to postpone the Olympics. oregonlive, "Shannon Rowbury is undaunted by the coronavirus or Olympics postponement: Oregon track & field rundown," 25 Mar. 2020 If that stream freezes up again or changes flow dramatically, the fish will react one way or another. Bill Heavey, Field & Stream, "How to Catch a Mess of Jumbo Perch," 25 Mar. 2020 Other Ohio cities reacted Cleveland was slow to the respond to the Spanish flu and suffered the worst death rate in Ohio. Cameron Knight,, "What were Cincinnati's tactics during the 1918 Spanish flu and did they work?," 24 Mar. 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

31 Mar 2020

Cite this Entry

“React.” Dictionary, Merriam-Webster, Accessed 1 Apr. 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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