internationalismPronunciation: /ɪntəˈnaʃ(ə)n(ə)lɪz(ə)m/Definition of internationalism noun [mass noun] 1the state or process of being international:the internationalism of popular music the advocacy of cooperation and understanding between nations. 2 (Internationalism) the principles of any of the four Internationals. Derivatives internationalist noun internationalism in other Oxford dictionaries Definition of internationalism in the US English dictionary