What does react mean?
React means to respond to something that happens, with a reaction that may be emotional, physical, verbal, or practical. People react to news, respond to pressure, and act in opposition when they react against injustice. The verb can also describe a process in chemistry: one substance reacts with another, producing a chemical change. In everyday language, the word often suggests a noticeable or immediate response, but it can also refer to a reaction that unfolds gradually. React is especially useful when the focus is on the connection between an event or stimulus and the resulting attitude or action. Its chemical sense follows the same underlying idea of one thing producing a response in another. The word is common in both British and American English and can be used across formal, scientific, political, and everyday registers.
To respond to a stimulus, event, or situation with an emotion, thought, or action; to act in opposition; or, in chemistry, to undergo a chemical change.
"The company reacted to the new regulations by revising its safety procedures."
The everyday sense commonly takes “to,” while the chemical sense commonly takes “with.” The verb is standard in British and American English.
A chemical substance or object that reacts or participates in a reaction.
"The react was separated from the products of the experiment."
This noun is uncommon outside technical or older scientific usage.
Plural forms are rare because the noun sense is chiefly technical and uncommon.
"The two reacts were mixed in a sealed container."
React literally means “act back”: its Latin ancestor combined re-, meaning “back,” with agere, meaning “do” or “drive.”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does react come from?
React comes from Latin reagere, formed from re-, meaning “back,” and agere, meaning “do,” “drive,” or “act.” The Latin verb originally conveyed the idea of acting back or driving back, a sense reflected in the word’s early English history. Its chemical meaning developed from this broader idea of reciprocal or resulting action, and it shares a root with English words such as action, active, agency, and agent.
Related word forms
How react is actually used
In everyday use, react is most often followed by “to”: react to news, react to pressure, or react with anger. In scientific contexts, “react with” introduces the other substance involved in the reaction. The verb can describe either an immediate response or a response developing over time.