What does reactive mean?
Reactive describes something that responds readily to a stimulus, change, or provocation. In science, it commonly refers to a substance or system that participates readily in chemical or physical reactions, as in “a highly reactive chemical.” In everyday descriptions of people or behaviour, it can indicate that someone reacts quickly, often emotionally, to events or criticism. The word is related to “react” and “reaction,” and its meaning always centres on responsiveness rather than action alone. It is especially useful in technical contexts, but it can also convey a negative implication when describing an easily startled or emotionally reactive person.
adjectiveResponding readily to a stimulus or change; tending to react. In chemistry and related fields, it describes a substance or system that participates readily in chemical or physical reactions.
- Responding readily to a stimulus or change.
- In chemistry or related sciences, undergoing or participating in chemical reactions readily.
- In descriptions of people or behaviour, responding quickly or emotionally to circumstances or provocation.
"The reactive surface of the catalyst caused the mixture to change colour almost immediately."
"The material is highly reactive when exposed to moisture."
"Her reactive response to the criticism surprised everyone in the room."
Reactive is the word for materials that refuse to sit still: they respond quickly to a change in their surroundings.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does reactive come from?
Reactive was formed in English from the verb “react” and the suffix “-ive,” a combination that developed during the 19th century. “React” ultimately comes from Latin, combining the prefix re-, meaning “back” or “again,” with agere, meaning “to do” or “to act.” Related English words include “reaction,” “reactor,” “action,” and “active,” all sharing this Latin root.
Related word forms
How reactive is actually used
The scientific senses are standard in British and American English. In descriptions of people, the word can imply a quick or emotional response and is sometimes mildly critical.
Easily confused with reactive
Active means engaged in action or activity, whereas reactive specifically means responding to a stimulus or tending to undergo reactions.
Inert describes something that does not react or undergo chemical change, while reactive describes something that responds or reacts readily.