counteract

verb

coun·​ter·​act ˌkau̇n-tər-ˈakt 

counteracted; counteracting; counteracts

transitive verb

: to make ineffective or restrain or neutralize the usually ill effects of by means of an opposite force, action, or influence

a drug used to counteract fatigue

counteraction

ˌkau̇n-tər-ˈak-shən 

noun

counteractive

ˌkau̇n-tər-ˈak-tiv 

adjective

Synonyms

• offset
• neutralize
• correct

Examples of counteract in a Sentence

The drug will counteract the poison.

this medication will counteract the symptoms but it won't kill the infection

Recent Examples on the Web

Share Dilution: The increase in shares outstanding by 6% to 10.8 billion has slightly counteracted the gains. —Trefis Team, Forbes.com, 29 Aug. 2025

Provides Antioxidants Riboflavin, an antioxidant, helps to counteract damage from toxins and disease in your body.11 Antioxidants help prevent many diseases, including heart disease, cancer, liver failure, and kidney disease. 6. —Heidi Moawad, Verywell Health, 27 Aug. 2025

San Jose State credited last year’s enrollment boost to the university’s proactive workshops, communication and staff efforts to counteract the national error. —Molly Gibbs, Mercury News, 27 Aug. 2025

Our Top Eye Creams for Puffy Eyes The good news: Certain eye creams can help counteract undereye puffiness. —Christa Joanna Lee, Allure, 22 Aug. 2025

Word History

First Known Use

1655, in the meaning defined above

Rhymes for counteract

• artefact
• artifact
• inexact
• interact
• noncontact
• reenact
• subcontract
• abstract
• attacked
• attract
• contact
• contract

Kids Definition

counteract

verb

coun·​ter·​act ˌkau̇nt-ə-ˈrakt 

: to lessen the force, action, or influence of : offset

a drug that counteracts a poison

counteraction

-ˈrak-shən 

noun

Medical Definition

counteract

transitive verb

coun·​ter·​act ˌkau̇nt-ə-ˈrakt 

: to make ineffective or restrain or neutralize the usually ill effects of by an opposite force

vitamin K counteracts the effects of warfarin

counteraction

-ˈrak-shən 

noun