re·​ac·​tive | \rē-ˈak-tiv \

Definition of reactive 

1 : of, relating to, or marked by reaction or reactance

2a : readily responsive to a stimulus

b : occurring as a result of stress or emotional upset reactive depression

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Other Words from reactive

reactively adverb
reactiveness noun
reactivity \(ˌ)rē-​ˌak-​ˈti-​və-​tē \ noun

Examples of reactive in a Sentence

The government's response to the problem was reactive rather than proactive.

Recent Examples on the Web

This shorter time to market means that the company can be reactive, adding extra server capacity near to where it's needed on demand. Peter Bright, Ars Technica, "Satya Nadella: The cloud is going to move underwater," 1 Nov. 2018 This instability makes the movement more reactive and harder to control. Jenny Mccoy, SELF, "Why You Should Add Hamstring Curls to Your Routine Like Celebrity Trainer Ashley Borden," 10 Oct. 2018 Trump’s belligerent and reactive tweeting has only intensified things, pushing North Korea to accelerate weapons testing. Ian Bremmer, Time, "The 5 Things to Know About the Thaw in Korean Relations," 16 Jan. 2018 In a non-reactive mixing bowl combine honey, sansho or spice mix and kosher salt. House Beautiful, "Honey Cured Salmon with Sansho Peppercorns, Goat Cheese, and Basil," 12 May 2011 Where Mr Macron telegraphs his plans early, loudly and clearly, Mrs Merkel is reactive and inscrutable. The Economist, "France's plans for euro-zone reform get a lukewarm German response," 9 June 2018 The rival Palestinian Authority was left to look reactive and meek by comparison. New York Times, "Killings in Gaza, New Embassy in Jerusalem, and Peace as Distant as Ever," 14 May 2018 Bigger picture, the Koch network wants to become less reactive and more proactive. James Hohmann, Washington Post, "The Daily 202: Koch network growing frustrated with the GOP’s 2018 agenda," 6 Apr. 2018 High-energy light from distant sources rarely makes it to Earth, because photons are so reactive they get lost along the way. Author: Sarah Kaplan, Anchorage Daily News, "In a cosmic first, scientists detect ‘ghost particles’ from a distant galaxy," 12 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'reactive.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of reactive

1717, in the meaning defined at sense 1

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Statistics for reactive

Last Updated

30 Nov 2018

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Time Traveler for reactive

The first known use of reactive was in 1717

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English Language Learners Definition of reactive

: done in response to a problem or situation : reacting to problems when they occur instead of doing something to prevent them

chemistry : tending to change into something else when mixed with another substance


re·​ac·​tive | \rē-ˈak-tiv \

Medical Definition of reactive 

1a : of, relating to, or marked by reaction reactive symptoms a reactive process

b : capable of reacting chemically highly reactive materials

2a : readily responsive to a stimulus the skin of the geriatric is less reactive than that of younger persons— Louis Tuft

b : occurring as a result of stress or emotional upset especially from factors outside the organism reactive depression

More from Merriam-Webster on reactive

Rhyming Dictionary: Words that rhyme with reactive

Britannica English: Translation of reactive for Arabic Speakers

Comments on reactive

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to enclose within walls

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