reactivity
noun
re·ac·tiv·i·ty
(ˌ)rē-ˌak-ˈti-və-tē 
: 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
Matt RidleyAbnormal 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
Bradford J. ShingletonExamples of reactivity in a Sentence
Recent Examples on the Web
In oxygen’s case, its outermost shell is two electrons short — comparatively fewer than other elements — and the configuration of those electrons contribute to oxygen’s high reactivity.
—Laura Poppick, Rolling Stone, 30 June 2025
Orange also developed canine reactivity, which the couple worked on with a professional dog trainer.
—Melissa Fleur Afshar, MSNBC Newsweek, 22 May 2025
The biggest takeaway for me is that proactivity leads to less reactivity.
—Georgia Godfrey, Forbes, 21 Jan. 2025
This outdated mentality fosters two counterproductive patterns: emotional repression, in which individuals suppress feelings, and emotional reactivity, where feelings are expressed impulsively and without regulation.
—Andriana Eliadis, Forbes.com, 20 June 2025
See All Example Sentences for reactivity
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Laura Poppick, Rolling Stone, 30 June 2025
Orange also developed canine reactivity, which the couple worked on with a professional dog trainer.
—Melissa Fleur Afshar, MSNBC Newsweek, 22 May 2025
The biggest takeaway for me is that proactivity leads to less reactivity.
—Georgia Godfrey, Forbes, 21 Jan. 2025
This outdated mentality fosters two counterproductive patterns: emotional repression, in which individuals suppress feelings, and emotional reactivity, where feelings are expressed impulsively and without regulation.
—Andriana Eliadis, Forbes.com, 20 June 2025
See All Example Sentences for reactivity
Cite this Entry
“Reactivity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/reactivity. Accessed 14 Jul. 2025.
Copy CitationMedical Definition
reactivity
noun
re·ac·tiv·i·ty
(ˌ)rē-ˌak-ˈtiv-ət-ē
plural reactivities
: the quality or state of being reactive
skin reactivity
emotional reactivity
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