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

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 On skin care being a priority: My philosophy is to be proactive instead of reactive. Kathleen Hou, The Cut, "How Model Denise Bidot Gets Glowy, Non-Puffy Skin," 11 July 2018 Congedo said the coalition will be proactive and reactive. Sarah Brookbank,, "Stand Against Racism event Friday to highlight courage, new coalition," 23 Apr. 2018 His point of view was rooted in the idea that American foreign and domestic policy should be proactive, not reactive. Jane Coaston, Vox, "Charles Krauthammer was the anti-Breitbart conservative writer," 21 June 2018 But this strike appeared to be pre-emptive, not reactive. The Economist, "Israel is determined to stop Iran from establishing bases in Syria," 12 Apr. 2018 Security measures must be preventative, not reactive. Aubrey Nagle,, "Cosby paid accuser $3.4M, Temple neighbors balk at community center 'bribe' | Morning Newsletter," 10 Apr. 2018 This was reactive soccer played proactively, and thanks to Kylian Mbappé, France can sit back and counter with a lightning bolt of its own. Brian Straus,, "Le Bleuprint: France Follows Familiar World Cup Path in Reaching Final," 10 July 2018 An infection might sweep through a community and pick out the children who are over-reactive carriers of pre-leukaemia cells. The Economist, "Germ-free children may be more prone to leukaemia," 24 May 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

7 Sep 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

See words that rhyme with reactive

Britannica English: Translation of reactive for Arabic Speakers

Comments on reactive

What made you want to look up reactive? Please tell us where you read or heard it (including the quote, if possible).


not any or not one

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