Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
counteractive is an adjective meaning "opposing or neutralizing or mitigating an effect by contrary action". It carries one recorded sense.
opposing or neutralizing or mitigating an effect by contrary action
Definitions, synonyms and semantic relations for counteractive come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.