react

verb

re·​act rē-ˈakt 

reacted; reacting; reacts

intransitive verb

1

: to exert a reciprocal or counteracting force or influence

—often used with on or upon

2

: to change in response to a stimulus

3

: to act in opposition to a force or influence

—usually used with against

4

: to move or tend in a reverse direction

5

: to undergo chemical reaction

transitive verb

: to cause to react

Synonyms of react

• respond

Examples of react in a Sentence

When I told her what happened, she reacted with anger.

I didn't expect him to react that way.

The firefighters reacted quickly when they heard the alarm.

He reacted badly to the drug.

Recent Examples on the Web

Australia has a history of reacting quickly to gun violence with legislation, and many have credited a ban on rapid-fire long guns brought in following a 1996 mass-shooting with sharply reducing death in the years since. —CBS News, 15 Dec. 2025

Reiner created a set so that all the participants could actually conduct the call live and react to each other. —Sandra Gonzalez, CNN Money, 15 Dec. 2025

Some outlets, including CNN, have regularly featured Epstein survivors and their attorneys reacting to new developments. —Stephanie A, The Conversation, 15 Dec. 2025

Lawmakers around the world react Reactions to the tragedy from lawmakers and other political figures have poured in from across the globe. —Michael Collins, USA Today, 15 Dec. 2025

Word History

Etymology

New Latin reactus, past participle of reagere, from Latin re- + agere to act — more at agent

First Known Use

1644, in the meaning defined at intransitive sense 1

Phrases Containing react

• react against

Rhymes for react

• abstract
• attacked
• attract
• contact
• contract
• detract
• distract
• enact
• exact
• extract
• hijacked
• impact

Kids Definition

react

verb

re·​act rē-ˈakt 

1

: to act or behave in response (as to stimulation or an influence)

the colonists reacted to the tax by boycotting tea

2

: to oppose a force or influence

—usually used with against

reacted against their unfair treatment

3

: to go through or cause to go through a chemical reaction

Medical Definition

react

intransitive verb

re·​act rē-ˈakt 

1

: to respond to a stimulus

2

: to undergo chemical reaction

transitive verb

: to cause to react