CongregationalismPronunciation: /kɒŋgrɪˈgeɪʃ(ə)n(ə)lɪz(ə)m/Definition of Congregationalism noun [mass noun] a system of organization among Christian churches whereby individual local churches are largely self-governing. Derivatives Congregationalist noun & adjective Congregationalism in other Oxford dictionaries Definition of Congregationalism in the US English dictionary