counteract

American

[koun-ter-akt] / ˌkaʊn tərˈækt /

verb (used with object)

to act in opposition to; frustrate by contrary action.

Synonyms:

thwart, contravene, counterbalance, neutralize

counteract British

/ ˌkaʊntərˈækt /

verb

(tr) to oppose, neutralize, or mitigate the effects of by contrary action; check

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

counteractant adjective
counteracter noun
counteractingly adverb
counteraction noun
counteractive adjective
counteractively adverb
counteractor noun
noncounteractive adjective
uncounteracted adjective

Etymology

Origin of counteract

First recorded in 1670–80; counter- + act

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

"Physical activity, such as resistance training, is important to counteract potential negative effects on muscle strength," he added.

From BBC • Mar. 31, 2026

None of it did much to counteract the sense that life had become too expensive.

From Slate • Mar. 25, 2026

Former Manchester City goalkeeper Shay Given suggested earlier this season that keeping players up while defending corners could be an effective way to counteract Arsenal's threat.

From BBC • Mar. 11, 2026

In the new study, the team explored whether GLP-1 drugs could counteract this process and reopen the tiny blood vessels that become blocked.

From Science Daily • Mar. 4, 2026

It is designed this way so that we have speed to counteract the gravitational pull of Mars.

From "A Rover's Story" by Jasmine Warga

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023