re·​act | \rē-ˈakt \
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

Neymar reacted in hysterics, prompting a furious response from both benches., "Neymar Fires Back at Critics Trying to 'Undermine’ Him Following Play Acting Accusations," 3 July 2018 Upon hearing that news, his teammates Donovan Mitchell and Rudy Gobert reacted by quickly posting similar requests on Twitter — that being that Favors finally grabs a dinner check. Tim Reynolds, The Seattle Times, "Boogie Bomb: Warriors set to add DeMarcus Cousins to lineup," 3 July 2018 Donald Trump reacted angrily to Harley-Davidson’s decision to relocate the production of motorbikes for sale to Europe outside the United States. The Economist, "Business this week," 28 June 2018 In-car video of the incident showed that the safety driver onboard the SUV was looking away from the road prior to the collision and wasn’t able to react fast enough to take steps to avoid it. Gary Gastelu, Fox News, "Uber announces end of self-driving car operations in Arizona," 23 May 2018 Serena Williams reacts after beating Julia Goerges. Tom Perrotta, WSJ, "Serena Williams Is Making Her Toughest Comeback Look Easy," 12 July 2018 Wisconsin's governor, congressional delegation and U.S. Senate candidates reacted Monday night to President Donald Trump's decision to replace Supreme Court Justice Anthony Kennedy with Brett Kavanaugh. Meg Jones, Milwaukee Journal Sentinel, "Wisconsin politicians and candidates weigh in on Supreme Court nominee," 9 July 2018 Bad Bunny, who is currently on vacation, took a couple of days to react after the big news. Suzette Fernandez, Billboard, "Bad Bunny Reacts to His First Hot 100 No. 1: 'Latinos Will Conquer the World'," 5 July 2018 Bayleigh Dayton of Lee’s Summit reacted after being named 2017 Miss Missouri USA. Conner Mitchell, kansascity, "After winning Miss Missouri, Lee's Summit woman faces a new contest: 'Big Brother'," 26 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

11 Nov 2018

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 \
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 \

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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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).


to express warning or disapproval

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