reactivity

noun

re·​ac·​tiv·​i·​ty (ˌ)rē-ˌak-ˈti-və-tē How to pronounce reactivity (audio)
: 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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Regular step-ups are great for training your leg muscles, but adding the power component helps train your reactivity and ability to produce force a little faster. — Jakob Roze, HEALTH, 28 Oct. 2026 Moreover, research in Emotion Review found that secure attachment was linked to lower emotional reactivity and faster emotional recovery. — Alex Vance, Parents, 25 Oct. 2026 Even some creators being paid to love their estrogen creams are fairly measured when reporting their results, which include less reactivity and more hydration. — Ashley Abramson, Allure, 22 Oct. 2026 As the test progressed, the team recorded a subcritical reactivity measurement at a peak core temperature of 1,852°F. — Aman Tripathi, Interesting Engineering, 22 Oct. 2026 See All Example Sentences for reactivity

Word History

First Known Use

1832, in the meaning defined above

Time Traveler
The first known use of reactivity was in 1832

Phrases Containing reactivity

Rhymes for reactivity

See All Rhymes for reactivity

Browse Nearby Words

reactive volt-amperes
reactivity
reactological
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Cite this Entry

“Reactivity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/reactivity. Accessed 1 Nov. 2026.

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Medical Definition

reactivity

noun
re·​ac·​tiv·​i·​ty (ˌ)rē-ˌak-ˈtiv-ət-ē How to pronounce reactivity (audio)
plural reactivities
: the quality or state of being reactive
skin reactivity
emotional reactivity
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