react
Americanverb (used without object)
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to act in response to an agent or influence.
How did the audience react to the speech?
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to act reciprocally upon each other, as two things.
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to act in a reverse direction or manner, especially so as to return to a prior condition.
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to act in opposition, as against some force.
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to respond to a stimulus in a particular manner.
reacting to a shock by jumping; to react to the word “coward” with anger.
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to undergo a chemical reaction.
verb
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(intr; foll by to, upon etc) (of a person or thing) to act in response to another person, a stimulus, etc, or (of two people or things) to act together in a certain way
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to act in an opposing or contrary manner
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(intr) physics to exert an equal force in the opposite direction to an acting force
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chem to undergo or cause to undergo a chemical reaction
Other Word Forms
Inflected Forms
Participles
Conjugated Forms
Present
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reactsimple
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reactssimple
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have reactedperfect
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has reactedperfect
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am reactingprogressive
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are reactingprogressive
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is reactingprogressive
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have been reactingperfect progressive
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has been reactingperfect progressive
Past
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reactedsimple
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had reactedperfect
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was reactingprogressive
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were reactingprogressive
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had been reactingperfect progressive
Future
Etymology
Origin of react
First recorded in 1635–45; re- + act, probably modeled on Medieval Latin reagere
Explanation
When you react to something, you respond to it. If someone pokes you in class, you might react by sticking out your tongue at them. The teacher might then react by giving you both detention. If someone says to you, "act, don't react," they are telling you not to automatically respond to something that someone does. Instead, you should think about it first and then decide what you want to do. In science, the word react is used to describe what happens when two substances combine and cause a chemical change in each other. When you add baking soda to vinegar, the chemicals in each react and create a foamy lava like substance.
Vocabulary lists containing react
Academic Vocabulary Toolkit 1, Words 71-80
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Word Generation Weekly - Series 1
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"Building Bridges" and "The Right Words at the Right Time"
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
How will he react when 185 million microphones are pointed at him?
From Los Angeles Times • Jun. 24, 2026
He acknowledged that investors could react negatively without enough clarity into the deals.
From MarketWatch • Jun. 22, 2026
Sometimes we react to injustice or betrayal by treating any foray into gradations as if it’s an existential threat to progress.
From The Wall Street Journal • Jun. 21, 2026
If we are to conserve primate species today, we need to know how they are threatened and how they will react to those threats.
From Science Daily • Jun. 20, 2026
Father did not react when another jostled him.
From "In the Year of the Boar and Jackie Robinson" by Bette Bao Lord
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
