countermeasure UK /ˈkaʊ̯ntəmɛʒə/US /ˈkaʊ̯ntɚmɛʒɚ/ noun2 •Any action taken to counteract or correct another.We fear that this will be the beginning of a negative development of measures and countermeasures, at the end of which there will be no winner — 2018 •[in the plural] Any of the devices and techniques used to impair the operational effectiveness of an enemy. formscountermeasures