counteract

verb

coun·​ter·​act ˌkau̇n-tər-ˈakt How to pronounce counteract (audio)
counteracted; counteracting; counteracts
Synonyms of counteractnext

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 How to pronounce counteract (audio)
noun
counteractive
ˌkau̇n-tər-ˈak-tiv How to pronounce counteract (audio)
adjective

Synonyms of counteract

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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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Creatine supplements may help counteract some of these changes by supporting muscle strength, mass and recovery, as well as brain health. — Maggie Ryan, Flow Space, 15 Oct. 2026 Paxton and Husted in particular demonstrate the GOP disadvantage at the candidate level, although the Republican super PAC spending in Texas and Ohio is intended to counteract it. — semafor.com, 15 Oct. 2026 To ensure its two onboard cameras capture essential imagery during the descent, the probe will rely on an attitude-control system to counteract any post-separation spin, Alhammadi said. — Sharmila Kuthunur, Space.com, 12 Oct. 2026 Elevate your legs This zero-cost prevention tactic simply counteracts the force of gravity. — Erica Sloan, Washington Post, 10 Oct. 2026 See All Example Sentences for counteract

Word History

First Known Use

1655, in the meaning defined above

Time Traveler
The first known use of counteract was in 1655

Rhymes for counteract

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Browse Nearby Words

counteraccusation
counteract
counteractant
See all Nearby Words

Cite this Entry

“Counteract.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/counteract. Accessed 19 Oct. 2026.

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Kids Definition

counteract

verb
coun·​ter·​act ˌkau̇nt-ə-ˈrakt How to pronounce counteract (audio)
: to lessen the force, action, or influence of : offset
a drug that counteracts a poison
counteraction
-ˈrak-shən How to pronounce counteract (audio)
noun

Medical Definition

counteract

transitive verb
coun·​ter·​act ˌkau̇nt-ə-ˈrakt How to pronounce counteract (audio)
: 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 How to pronounce counteract (audio)
noun
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