counterterrorism Syllabification: (coun·ter·ter·ror·ism)Pronunciation: /ˌkountərˈterəˌrizəm/Definition of counterterrorism noun political or military activities designed to prevent or thwart terrorism. Derivatives counterterroristPronunciation: /ˌkountərˈterərist/ noun & adjective counterterrorism in other Oxford dictionaries Definition of counterterrorism in the British & World English dictionary