reactive
Americanadjective
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tending to react.
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pertaining to or characterized by reaction.
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Electricity. pertaining to or characterized by reactance.
adjective
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readily partaking in chemical reactions
sodium is a reactive metal
free radicals are very reactive
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of, concerned with, or having a reactance
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responsive to stimulus
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(of mental illnesses) precipitated by an external cause
reactive depression
Other Word Forms
- antireactive adjective
- hyperreactive adjective
- nonreactive adjective
- overreactive adjective
- reactively adverb
- reactiveness noun
- reactivity noun
- unreactive adjective
Etymology
Origin of reactive
Explanation
To be reactive is to be ready to react or respond to something else — as opposed to ready to act on one's own. A person who's reactive does things only in response to others. To react is to do something in response to something else. When someone pinches you, for example, you react. But if you're a reactive person, then you only react; you're always ready to react but not to act on your own. You're rather lifeless unless something or someone else causes you to do act. This is usually seen as a negative trait in people, unless you're talking about, say, firefighters or cops. We admire people who don't need prodding to get things done. Some chemicals are called reactive, too, because they react readily with other chemicals.
Vocabulary lists containing reactive
Chemical Reactions - Introductory
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The State of the Union Address 2015
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Matter and Energy 2: Properties of Matter, Chemical Reactions, and Energy
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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.
The wide-ranging proposals say reactive action would be insufficient, and online marketplaces would need to "act with due care to prevent, identify and remove dangerous products being sold via their platforms".
From BBC • Apr. 15, 2026
“Whether people are tracking food intake, monitoring sleep or asking about peptide therapies, they’re expressing the same underlying shift: from reactive to proactive,” Jeffrey Egler, Noom’s chief medical officer, said in an email last week.
From MarketWatch • Apr. 15, 2026
He describes it as "a suit of armor," designed to shield the reactive center from water and other nearby molecules.
From Science Daily • Apr. 11, 2026
The point of all this: AI is helping course managers be proactive regarding the pace of play rather than reactive.
From The Wall Street Journal • Apr. 10, 2026
The chemosterilants of this group are alkylating agents, which are extremely reactive chemicals, capable of intense cell destruction, damage to chromosomes, and production of mutations.
From "Silent Spring" by Rachel Carson
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.
