Synonyms

reactivity

American

[ree-ak-tiv-i-tee] / ˌri ækˈtɪv ɪ ti /

noun

the quality or condition of being reactive.
Chemistry. the relative capacity of an atom, molecule, or radical to undergo a chemical reaction with another atom, molecule, or compound.
Physics. a measure of the deviation from the condition at which a nuclear reactor is critical.
Immunology. the ability of an antigen to combine with an antibody.

Other Word Forms

hyperreactivity noun

Etymology

Origin of reactivity

First recorded in 1885–90; reactive + -ity

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Paris police chief Patrice Faure paid tribute to "the reactivity and the mobilisation" of the investigators that led to the arrest of the suspect.

From Barron's • Dec. 27, 2025

It lets you step out of the tornado of reactivity and remember who you are.

From Salon • Nov. 22, 2025

This change, known as lattice nitrogen reactivity, influences the way molecules vibrate, known as their vibrational properties.

From Science Daily • Nov. 6, 2025

“We told Jack we needed a special person to handle this dog,” says Padilla, referencing Felisha’s fear-based reactivity.

From Los Angeles Times • Jul. 21, 2025

Too much reactivity and we would spontaneously combust.

From "The Gene" by Siddhartha Mukherjee

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023