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

Instead of driving proactive change, leaders feel stuck in cycles of reaction, burnout, and reactivity. —Lisa Bodell, Forbes.com, 13 Aug. 2025

Higher reactivity to guests was partly explained by small size and being allowed on the bed. —New Atlas, 7 Aug. 2025

These dogs have some innate positive traits (primarily that calmness and low reactivity), but the negative effects of small size and lack of training can negate them. —Laura Baisas Aug 6, Popular Science, 6 Aug. 2025

This mindset shift unlocks abundance and buffers against reactivity. —Bala Sathyanarayanan, Forbes.com, 4 Aug. 2025

Word History

First Known Use

1832, in the meaning defined above

Phrases Containing reactivity

• hyper-reactivity

Rhymes for reactivity

• absorptivity
• affectivity
• collectivity
• conductivity
• connectivity
• corrosivity
• creativity
• diffusivity
• directivity
• effectivity
• emissivity
• exclusivity

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