coun·ter·act (koun'tər-ākt') tr.v.
coun·ter·act·ed, coun·ter·act·ing, coun·ter·acts To oppose and mitigate the effects of by contrary action; check. coun'ter·ac'tion n., coun'ter·ac'tive adj., coun'ter·ac'tive·ly adv.
Main Entry: coun·ter·act Pronunciation: "kaunt-&-'rakt Function: transitive verb : to make ineffective or restrain or neutralize theusually ill effects of by an opposite force counteract disease before medical science comes into play —Havelock Ellis> —coun·ter·ac·tion/-'rak-sh&n/noun