definition of
counteract

[1] #1 counteract v. [antagonize, antagonise] act in opposition to. wn

[2] #2 counteract v. [countercheck] oppose or check by a counteraction. wn

[3] #3 counteract v. [countervail, neutralize, counterbalance] oppose and mitigate the effects of by contrary actions; "This will counteract the foolish actions of my colleagues". wn

[4] #4 counteract v. [sabotage, undermine, countermine, subvert, weaken] destroy property or hinder normal operations; "The Resistance sabotaged railroad operations during the war". wn