react

verb

re·​act rē-ˈakt How to pronounce react (audio)
reacted; reacting; reacts
Synonyms of reactnext

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

Synonyms of react

Relevance
See All Synonyms & Antonyms in Thesaurus

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.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Those reacting on social media were divided over the concept. — Steve Scauzillo, Daily News, 7 Aug. 2026 The key is to define those conditions while thinking clearly, not while reacting to a rapidly moving market. — Brian Ferdinand, Forbes.com, 6 Aug. 2026 New York City Mayor Zohran Mamdani is reacting after voters in Michigan chose a progressive over a moderate in the Democratic Senate primary race there. — Jesse Zanger, CBS News, 6 Aug. 2026 When the identities of the Customs and Border Protection agents who killed Alex Pretti in January were revealed as those of two Hispanic men, many people reacted with shock. — Eladio Bobadilla, Mercury News, 6 Aug. 2026 See All Example Sentences for react

Word History

Etymology

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

First Known Use

1644, in the meaning defined at intransitive sense 1

Time Traveler
The first known use of react was in 1644

Phrases Containing react

Rhymes for react

See All Rhymes for react

Browse Nearby Words

reacquisition
react
react against
See all Nearby Words

Cite this Entry

“React.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/react. Accessed 8 Aug. 2026.

Copy Citation

Kids Definition

react

verb
re·​act rē-ˈakt How to pronounce react (audio)
1
: to act or behave in response (as to stimulation or an influence)
the colonists reacted to the tax by boycotting tea
2
: to oppose a force or influence
—usually used with against
reacted against their unfair treatment
3
: to go through or cause to go through a chemical reaction

Medical Definition

react

intransitive verb
re·​act rē-ˈakt How to pronounce react (audio)
1
: to respond to a stimulus
2
: to undergo chemical reaction

transitive verb

: to cause to react

More from Merriam-Webster on react

Nglish: Translation of react for Spanish Speakers

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of nurture

See Definitions and Examples »

Popular in Grammar & Usage

See More

7 Pairs of Commonly Confused Words

Merriam-Webster’s Great Big List of Words You Love to Hate

Is it 'nerve-racking' or 'nerve-wracking'?

'Sneaked' or 'Snuck': Which is correct?

Why does English have so many silent letters?
See More

Popular in Wordplay

See More

The Longest Long Words List

It's a Scorcher! Words for the Summer Heat

14 Phobias You Probably Haven't Heard Of

The Words of the Week - Aug. 7

How long is a jiffy?
See More

Popular

See More

7 Pairs of Commonly Confused Words

The Longest Long Words List

It's a Scorcher! Words for the Summer Heat
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
fridge-magnet-letters
Drop a Letter Quiz August 2026 Drop a letter from a word to make a totally diffe...
See All