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

Despite their distinct appearances, both sides are exactly the same in terms of function and reactivity with food. —Darcy Lenz, Southern Living, 24 Sep. 2025

At the heart of this research is the quantum many-body problem, which describes how electrons interact – critical for determining chemical bonds, reactivity, and electrical behavior. —Bojan Stojkovski, Interesting Engineering, 21 Sep. 2025

Some people, particularly those with latex allergies due to cross-reactivity, may also experience allergic reactions to the fruit such as throat itching, lip or tongue swelling, hives or even breathing difficulties. —Daryl Austin, USA Today, 20 Sep. 2025

For generations, the healthcare system has been defined by its reactivity. —Kent Dicks, Forbes.com, 16 Sep. 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