verb (used with object)

to act in opposition to; frustrate by contrary action.

Origin of counteract

First recorded in 1670–80; counter- + act
Related formscoun·ter·ac·tant, adjectivecoun·ter·act·er, coun·ter·ac·tor, nouncoun·ter·act·ing·ly, adverbcoun·ter·ac·tion, nouncoun·ter·ac·tive, adjectivecoun·ter·ac·tive·ly, adverbnon·coun·ter·ac·tive, adjectiveun·coun·ter·act·ed, adjective

Synonyms for counteract Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for counteract

Contemporary Examples of counteract

Historical Examples of counteract

  • He does not wish me to be there without his presence to counteract my evil influences.

    Wilfrid Cumbermede

    George MacDonald

  • This impression, however, I found I could counteract the moment I had time for reflection.

    Patrick Henry

    Moses Coit Tyler

  • To no end did Barrington exert himself to conceal or counteract this frigidity.


    Charles James Lever

  • Warnings have been broadcasted, but there are no stocks of chemicals that might counteract it.

  • Hence, we must counteract the ocular deception by an adjustment of proportions.

British Dictionary definitions for counteract



(tr) to oppose, neutralize, or mitigate the effects of by contrary action; check
Derived Formscounteraction, nouncounteractive, adjectivecounteractively, adverb
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

Word Origin and History for counteract

1670s, from counter- + act (v.). Related: Counteracted; counteracting.

Online Etymology Dictionary, © 2010 Douglas Harper