What does reactivity mean?
Reactivity is the quality of responding readily to a stimulus, a change in circumstances, or another substance. In chemistry, it refers especially to the ability of a material to undergo a chemical reaction; highly reactive substances may react quickly or vigorously, while less reactive ones require stronger conditions. In biology and psychology, the word describes the degree to which an organism or person responds to changes, stress, or other stimuli. More broadly, emotional reactivity can imply that someone reacts quickly and intensely to criticism or difficulty. The word is consequently both technical and evaluative: it can describe measurable properties in scientific contexts, but also suggest a sensitive or excitable temperament in ordinary discussion.
nounThe quality or degree of being reactive: readiness to respond to stimuli, or, in chemistry, the tendency or ability to undergo chemical change.
- In chemistry, the property of a substance that determines how readily it undergoes a chemical reaction.
- In biology or psychology, the degree to which an organism or person responds to a stimulus.
- In general use, a tendency to react quickly or strongly to circumstances, criticism, or change.
"The reactivity of alkali metals increases down the group."
"The reactivity of alkali metals increases down the group."
"Her emotional reactivity made the disagreement more intense than it needed to be."
The plural is uncommon, especially in general writing; the singular is often preferred when discussing the property as a whole.
"Researchers compared the reactivities of several catalysts."
A material's reactivity reveals not just what it is, but how readily it responds to change—a crucial clue in chemistry and biology.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does reactivity come from?
The noun combines the stem react- with the suffix -ity, which forms abstract nouns from adjectives. React comes through French réactif from Latin reactivus, built from re-, meaning back or again, and activus, meaning active; activus is related to agere, to do or act. Reactivity therefore shares its origin with reaction, reactive, and reactor.
How reactivity is actually used
Most common in chemistry, biology, psychology, and related technical fields. In general use, it often suggests a strong or rapid response and may carry a slightly clinical or evaluative tone.
Easily confused with reactivity
Reactive is an adjective describing something that responds readily, whereas reactivity is the noun naming the quality or degree of responding.