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 immune system may show signs of how strongly it will react even before vaccination.
From Science Daily ● Aug. 21, 2026
Bandelier says that hedge funds have expressed interest in trading event contracts tied to iPhone sales rather than trying to anticipate how Apple shares will react to sales numbers.
From The Wall Street Journal ● Aug. 19, 2026
Per Mortgage News Daily data, the 30-year mortgage rate has yet to react so strongly.
From MarketWatch ● Aug. 18, 2026
How quickly the brain and body react after tripping — with your foot automatically thrusting forward, for example, to prevent yourself from face-planting — is what plyometrics trains for.
From Los Angeles Times ● Aug. 18, 2026
“We’d had two months of warning, but nothing on a socially useful timescale, where you can react and do enough. Months are too long, and seconds are too short,” said Malone.
From "Mountain of Fire" by Rebecca E. F. Barone
The Tesla’s cameras can see jaywalkers before I do, oncoming headlights don’t blind it, and the car reacts faster than I can.
From The Wall Street Journal ● Aug. 4, 2026
The technology can operate with fuels other than hydrogen, but hydrogen is especially suitable because it reacts very quickly and can produce stable increases in pressure.
From Science Daily ● Aug. 4, 2026
As that acidic water reacts with certain rocks -- limestone, for instance -- it releases carbon dioxide into the atmosphere.
From Barron's ● Jul. 22, 2026
Finally, as with all previous administrations, how a Burnham-led government reacts to events beyond its control may have the biggest impact on the money in people's pockets.
From BBC ● Jul. 20, 2026
He never reacts under great suffering, never gets angry, is never threatening.
From "Americanah" by Chimamanda Ngozi Adichie
Neither the DRC nor M23 authorities have yet reacted to the announcement of the mission.
From Barron's ● Aug. 24, 2026
Samsung Electronics stock had its worst day in three weeks on Monday as investors reacted to its shareholder-return plan, souring the mood for other memory-chip making rivals.
From MarketWatch ● Aug. 24, 2026
Those cells showed widespread changes in gene activity, including shifts in how they processed fuel, reacted to hormones, and detected nutrient availability.
From Science Daily ● Aug. 21, 2026
Other U.S. allies in the region reacted swiftly to Trump’s pullback from the Korean exercises.
From Los Angeles Times ● Aug. 19, 2026
His body reacted to the shock of his situation.
From "Just Mercy" by Bryan Stevenson
Micron stock was reacting to news that Apple has tested memory chips from China’s ChangXin Memory Technologies.
From Barron's ● Aug. 10, 2026
They were reacting to the little passes between Tielemans and Fernandes, which allowed United to ease their way out of trouble or move up the pitch.
From BBC ● Aug. 8, 2026
Rather than reacting only to familiar properties such as color or intensity, it detects subtle quantum distinctions in the incoming light.
From Science Daily ● Aug. 8, 2026
Jefferies analyst Samad Samana wrote in a Wednesday note that investors were reacting to more than just the “clean sweep” evidenced by Shopify’s results.
From MarketWatch ● Aug. 5, 2026
On Tuesday, November 1, newspaper editorial pages started reacting to the broadcast.
From "Spooked!" by Gail Jarrow
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.
