Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “react”

See all translations

react

verb [I] uk   /riˈækt/ us  
B2 to act in a particular way as a direct result of something else: She slapped him and called him names, but he didn't react. The judge reacted angrily to the suggestion that it hadn't been a fair trial. Many people react (badly) to (= are made ill by) penicillin. chemistry to change in a physical or chemical way when put with another substance: Potassium reacts with water.
More examples
Phrasal verbs
(Definition of react from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of react?
Add Cambridge dictionaries to your browser to your website

Definitions of “react” in other dictionaries

Word of the Day

christmassy

typical of Christmas, or happy because it is Christmas

Word of the Day

Cleavage proves divisive in Cambridge’s words of 2014

by Alastair Horne,
December 19, 2014
​​​​ Other dictionaries may choose faddish novelties as their words of the year, but here at Cambridge, we like to do something different. We look for the words that have seen sudden surges in searches over the course of the year – words that have been baffling users of English and driven them

Read More 

cinderella surgery noun

December 15, 2014
cosmetic surgery to the feet We have all heard of people having nose jobs, boob jobs and liposuction – but now a new trend growing in popularity in America: Cinderella surgery.

Read More