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

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

Neurocosmetic skincare is everywhere in 2026, with prestige brands and beauty editors promising formulas that work on the brain-skin axis to calm redness, dullness and reactivity. — Samantha Agate, Miami Herald, 28 Sep. 2026

Reactive Leadership Ineffective managers often get trapped in a cycle of reactivity, spending their days responding to problems rather than building a better future. — Expert Panel®, Forbes.com, 28 Sep. 2026

The experiment reached criticality at 1,225°F and produced a subcritical reactivity measurement at a peak core temperature of 1,852°F. — Aamir Khollam, Interesting Engineering, 15 Sep. 2026

Your brain activity shifts away from the regions that drive emotional reactivity and toward the prefrontal cortex, which is responsible for logical thinking. — Amy Morin, CNBC, 21 June 2026

Word History

First Known Use

1832, in the meaning defined above

Phrases Containing reactivity

• hyper-reactivity

Rhymes for reactivity

• acclivity
• activity
• captivity
• declivity
• festivity
• nativity
• passivity
• proclivity
• absorptivity
• affectivity
• collectivity
• conductivity

Medical 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