re·ac·tiv·i·ty | \(ˌ)rē-ˌak-ˈti-və-tē \

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

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 Parents are an integral piece in a powerful system for regulating children’s stress and emotional reactivity. Dylan Gee, Vox, "I study kids who were separated from their parents. The trauma could change their brains forever.," 20 June 2018 Scientists can look at the brains of young mammals — whether humans, rats, or monkeys — when they’re separated from their mothers and see reactivity in the amygdala, which controls the fight-or-flight response. Katherine Reynolds Lewis, The Cut, "Can Scientists Tell Me If I’m a Good Mom?," 17 Apr. 2018 Greater SB was associated with increased food cue reactivity. Sheah Rarback, miamiherald, "Sedentary behavior can trigger desire for high-calorie foods | Miami Herald," 2 Apr. 2018 For them, both Cognitive Behavioral Therapy (CBT) and mindfulness meditation can help reduce emotional reactivity and the impulse to impose one’s values on others. Philip Chard, Milwaukee Journal Sentinel, "Feeling disrespected pushes our buttons," 29 Mar. 2018 Those who’d slept and dreamed reported a marked decrease in their emotional response to the images, with a concurrent reduction in reactivity in the amygdala, the emotional center of the brain. Linda Rodriguez Mcrobbie,, "How our dreams made us human," 23 Mar. 2018 Indeed, studies show that an optimistic approach blunts reactivity to stress, curbing the outpouring of hormones that can debilitate body and mind. Hara Estroff Marano, New York Times, "What Does It Take to Overcome Adversity?," 12 Jan. 2018 Studies have shown that people with adverse childhood experiences are more likely to suffer from mental- and physical-health disorders, leading people to experience a chronic state of high stress reactivity. Cindy Lamothe, The Atlantic, "When Kids Have to Act Like Parents, It Affects Them for Life," 26 Oct. 2017

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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The first known use of reactivity was in 1832

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More Definitions for reactivity


re·ac·tiv·i·ty | \(ˌ)rē-ˌak-ˈtiv-ət-ē \
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).


a state of commotion or excitement

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