synergist Syllabification: (syn·er·gist)Pronunciation: /ˈsinərjist/Definition of synergist noun a substance, organ, or other agent that participates in an effect of synergy. Derivatives synergisticPronunciation: /ˌsinərˈjistik/ adjective synergisticallyPronunciation: /ˈˌsinərˈjistik(ə)lē/ adverb synergist in other Oxford dictionaries Definition of synergist in the British & World English dictionary