re·​ac·​tiv·​i·​ty | \ (ˌ)rē-ˌak-ˈti-və-tē How to pronounce reactivity (audio) \

Definition of reactivity

: the quality or state of being reactive emotional reactivity chemical reactivity If the brain, responding to psychological stress, stimulates the release of cortisol and cortisol suppresses the reactivity of the immune system, then a dormant viral infection may well flare up, or a new one catch hold.— Matt Ridley Abnormal reactivity to light and abnormal pupillary size may be important clues to the presence of cranial injury in the setting of head trauma.— Bradford J. Shingleton

Examples of reactivity in a Sentence

Recent Examples on the Web Additional attributes are the potential for epitope spread by increasing cross-reactivity to other virus strains, which can have a direct impact on breadth of virus coverage and enhanced cellular immunity13. William Warren, Scientific American, "Sanofi Pasteur: fighting influenza by improving today and innovating for tomorrow," 18 Sep. 2019 That speed and hyper-reactivity wasn’t there yet in the 2000s. Patrick Lyons, Billboard, "How Kanye, Taylor and the 2009 VMAs Changed Music and Culture Reporting," 13 Sep. 2019 The above is just a brief description on how to work with your dog’s reactivity to other dogs. Tasha Suda, The Mercury News, "Critter Corner: Controlling a dog’s anxiety when seeing other dogs on walks," 20 Aug. 2019 This slows your ability to process information and solve problems, kills your creativity, and increases your emotional reactivity. Dr. Travis Bradberry, Quartz at Work, "Nine skills you should learn that pay off forever," 13 Aug. 2019 Barrett is more than capable of making reads and delivering assists, but the issue might be that his game lacks a degree of reactivity and improvisation. Jeremy Woo,, "Top 10 Rookie Takeaways From NBA Summer League," 16 July 2019 The answer came to him in a dream: columns of similar reactivity and rows of ascending weight. Andrew Crumey, WSJ, "‘Mendeleyev’s Dream’ and ‘Elemental’ Review: Cracking the Chemical Code," 21 June 2019 This chemical reactivity, says McGonigal, looks a lot like the biology of courage. . Kate Branch, Vogue, "Now, Experts Say Stress Can Be Good for Your Health—Really," 18 Dec. 2018 Early in life, the mere presence of a parent reduces a child’s levels of cortisol, a major stress hormone, and downregulates their amygdala reactivity. Dylan Gee, Vox, "I study kids who were separated from their parents. The trauma could change their brains forever.," 20 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'reactivity.' 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 reactivity

1832, in the meaning defined above

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Time Traveler for reactivity

Time Traveler

The first known use of reactivity was in 1832

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Statistics for reactivity

Last Updated

18 Nov 2019

Cite this Entry

“Reactivity.” The Dictionary, Merriam-Webster Inc., Accessed 10 December 2019.

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More Definitions for reactivity


re·​ac·​tiv·​i·​ty | \ (ˌ)rē-ˌak-ˈtiv-ət-ē How to pronounce reactivity (audio) \
plural reactivities

Medical Definition of reactivity

: the quality or state of being reactive skin reactivity emotional reactivity

Comments on reactivity

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


to state or do over again or repeatedly

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