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

Just a few minutes of conscious breathing, focused attention and grounding movement is enough to help reconnect the mind and body, reduce reactivity and restore a sense of ease. —Dana Santas, CNN Money, 14 Jan. 2026

The team then tested the horses’ reactivity by opening an umbrella near a bucket of food. —Marta Hill, Scientific American, 14 Jan. 2026

Try to be patient, don’t take action out of emotional reactivity. —Kimberly King, Baltimore Sun, 3 Jan. 2026

Try to be patient, and don’t take action out of emotional reactivity. —Magi Helena, Dallas Morning News, 3 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