mutualismPronunciation: /ˈmjuːtʃʊəlɪz(ə)m, -tjʊə-/Definition of mutualism noun [mass noun] 1the doctrine that mutual dependence is necessary to social well-being. 2 Biology symbiosis which is beneficial to both organisms involved. Derivatives mutualist noun & adjective mutualisticPronunciation: /-ˈlɪstɪk/ adjective mutualisticallyPronunciation: /-ˈlɪstɪk(ə)li/ adverb mutualism in other Oxford dictionaries Definition of mutualism in the US English dictionary