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

Without transcendence, leadership drifts into reactivity and exhaustion. —Mary Crossan, Forbes.com, 28 Jan. 2026

Because of the low reactivity of fluorine, when KL-50 deposits fluoroethyl groups onto the cells, the crosslinks are slow to form. —Isabella Backman, Hartford Courant, 27 Jan. 2026

Heightened reactivity is possible today, time in quiet can help almost everything. —Tribune Content Agency, Baltimore Sun, 26 Jan. 2026

Heightened reactivity is possible today, and time in quiet can help almost everything. —Magi Helena, Dallas Morning News, 26 Jan. 2026

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