Main Entry:

coun·ter·act

Pronunciation:

\ˌkau̇n-tər-ˈakt\

Function:

transitive verb

Date:

1655

: to make ineffective or restrain or neutralize the usually ill effects of by means of an opposite force, action, or influence <a drug used to counteract fatigue>

— coun·ter·ac·tion \-ˈak-shən\ noun

— coun·ter·ac·tive \-ˈak-tiv\ adjective