coun·ter·act
ˌkau̇n-tər-ˈakt 
counteracted; counteracting; counteracts
: 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
coun·ter·ac·tion
¦kau̇n-tər-¦ak-shən
plural -s
1
: contrary action : opposition, resistance
scheming counteraction
2
: act or action of counteracting : a counteracting agency
the counteraction of centripetal forces on centrifugal tendencies
Examples of counteract in a Sentence
Verb
The drug will counteract the poison.
this medication will counteract the symptoms but it won't kill the infection
Recent Examples on the Web
Danielle Zickl, Health, 20 June 2026
Slovakia, like many other European countries, increased state spending to counteract the economic shocks of the COVID-19 pandemic and Russia’s war against Ukraine, which caused energy prices to spike.
—ABC News, 18 June 2026
When brands lose control of their voice thanks to a lack of guardrails, the impacts are quiet, gradual and difficult to counteract.
—Expert Panel®, Forbes.com, 18 June 2026
Hamilton expressed faith in the FEMA staff and praised the recent opening of 350 positions to counteract some of the cuts.
—Los Angeles Times, 17 June 2026
See All Example Sentences for counteract
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Verb
Antioxidants’ job is to counteract free radicals, which are unstable molecules that build up from stress, poor diet, or a sedentary lifestyle.
—Danielle Zickl, Health, 20 June 2026
Slovakia, like many other European countries, increased state spending to counteract the economic shocks of the COVID-19 pandemic and Russia’s war against Ukraine, which caused energy prices to spike.
—ABC News, 18 June 2026
When brands lose control of their voice thanks to a lack of guardrails, the impacts are quiet, gradual and difficult to counteract.
—Expert Panel®, Forbes.com, 18 June 2026
Hamilton expressed faith in the FEMA staff and praised the recent opening of 350 positions to counteract some of the cuts.
—Los Angeles Times, 17 June 2026
See All Example Sentences for counteract
Cite this Entry
“Counteract.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/counteract. Accessed 21 Jun. 2026.
Copy CitationKids Definition
counteract
verb
coun·ter·act
ˌkau̇nt-ə-ˈrakt
: to lessen the force, action, or influence of : offset
a drug that counteracts a poison
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
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