Simple past tense and past participle of counteract.(verb)
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Use "counteracted" in a sentence
"The only way the republican manufactured pseudo-grass roots revolt against President Obama can be effectively counteracted is for those of us who supported him and voted for him to stand with him now and fight back with our words AND actions."
"But surely no one expects readers to be converted to Nazism or sadomasochism through Aue's account of himself, either, so one must conclude that Franklin's and Bukiet's dislike of an "unremitting immersion in Aue's worldview" has been converted into a general critical requirement that bad people as depicted in fiction must be "counteracted" by a "philosophical or artistic" effort to meliorate their evil."
"The effects of every change in a firm's financial asset structure on the stockholders 'portfolios can be "counteracted" by changes in the stockholders' own portfolios."