react
Americanverb (used without object)
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reacts,
present (3rd person singular)
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reacted,
past participle, past
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reacting
present participle
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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
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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.
See Examples For:
The trucks use lidar to see more clearly in the dark, dust and foggy weather and can react faster or avoid a hazard.
From The Wall Street Journal ● Oct. 17, 2026
Arizona is far from the only state to see politicians react to data centre backlash.
From BBC ● Oct. 14, 2026
The Seoul National University team's findings indicate that controlling the tiny environment where molecules actually react may be just as important.
From Science Daily ● Oct. 12, 2026
Inconsistent, often slow to react, but mostly he’s unable to finish.
From Los Angeles Times ● Oct. 10, 2026
“I want to understand how crises work, how governments react, everything.”
From "Most Dangerous: Daniel Ellsberg and the Secret History of the Vietnam War" by Steve Sheinkin
Loretta Mester, who as Cleveland Fed president from 2014 to 2024 called for the institution to explain how it reacts to economic developments, said the episode showed the limits of leaving markets to guess.
From The Wall Street Journal ● Oct. 6, 2026
Roy Keane: Foden gets up and reacts obviously, so he's sent off.
From BBC ● Sep. 13, 2026
Scientists from ECU's School of Engineering found that magnetite can release hydrogen gas when it reacts with hot water under conditions similar to those deep below the Earth's surface.
From Science Daily ● Aug. 29, 2026
The chemical deployed by Wallace during her investigation reacts with the iron in hemoglobin, a protein found in red blood cells.
From Los Angeles Times ● Jul. 22, 2026
“It all works out,” said Lee, “true to outrageous form. It’s kind of insulting that everyone reacts about the same way.”
From "East of Eden" by John Steinbeck
For example, some agents reacted to sounds or recognized the emotional states of others.
From Science Daily ● Oct. 14, 2026
Reyes believes the pair agitated the dog, who reacted in self-defense.
From Los Angeles Times ● Oct. 13, 2026
Investors may have reacted prematurely in selling chip stocks over fears about OpenAI’s financial position.
From MarketWatch ● Oct. 9, 2026
Fans reacted with anger when some of the ticket price rises for major events next year were announced earlier this summer.
From BBC ● Oct. 8, 2026
I had reacted as apologetically as I possibly could, but this was way too much.
From "Just Mercy" by Bryan Stevenson
In June, a US plan to establish an Ebola treatment facility at a military base in the central Kenyan town of Nanyuki sparked concern, with Kenyans reacting furiously about the risks of cross-border infection.
From BBC ● Oct. 7, 2026
But then the Russians doubled the number of antennas from four to eight, then to 16, and now to 32, each time reacting to new Lima updates.
From The Wall Street Journal ● Oct. 6, 2026
At the same time, water molecules surrounding the reacting molecules constantly shift and reorganize in ways that are notoriously difficult to observe directly.
From Science Daily ● Oct. 6, 2026
News is reacting to what students and families are saying they want from college, said Robert Kelchen, a professor who studies higher education at the University of Tennessee.
From MarketWatch ● Sep. 22, 2026
He spins in his chair to see Finnick and me reacting to his words.
From "Mockingjay" by Suzanne Collins
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Get a wordDefinitions 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.
