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

• reply
• 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

Supporters react as Democratic presidential nominee, U.S. Vice President Kamala Harris, concedes the election during a speech at Howard University on Nov. 6, 2024, in Washington, DC. —Julia Prodis Sulek, The Mercury News, 7 Nov. 2024

Supporters react to election results at Howard University. —Curtis Bunn, NBC News, 6 Nov. 2024

Many celebs are reacting with frustration and disappointment after the decisive Republican victory. —Jennifer Zhan, Vulture, 6 Nov. 2024

Gratitude can help foster long-term thinking by reducing the tendency to react impulsively in the heat of the moment. —Raquel Gomes, Forbes, 5 Nov. 2024

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

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