Italian Fascism denotes the authoritarian, nationalist, Fascismo politics via which Prime Minister Benito Mussolini ruled the Kingdom of Italy, from 1922 until 1943. Etymologically, Fascismo (Fascism) derives from the Italian fascio (league), derived from the Latin fasces (bundles); the ancient Roman Symbol of Authority. It dates from Mussolini’s January 1915 coinage and the 1919 establishment of the Fascist Revolutionary Party begun as the fasci di combattimento (combat leagues) popular movement. The English fascism denotes the league connotation of the Italian fascio (fagot); in the Italian language, in denoting the political philosophy, the proper noun Fascismo (Fascism) is upper-case, and the generic, common noun fascismo (fascism) is lower-case.

In political science, Italian Fascism is the syncretic model of government from which derive other varieties of fascism — yet they share no common politico-philosophic core, a “fascist minimum” of tactical, cultural, and ideological tenets. During the twenty-one-year intermarium of the First (1914–18) and Second (1939–45) world wars, similarly authoritarian–nationalist movements appeared worldwide: Adolf Hitler’s Nazism in Germany, Peronism in Argentina under General Juan Domingo Perón, Falangism in Spain under Generalissimo Francisco Franco, the Iron Guard in Romania, Integralism in Brazil, Action Française and the Croix-de-Feu in France, the Arrow Cross Party in Hungary, Austrofascism in the Austria of Engelbert Dollfuss, Statism in Shōwa Japan, Rexism in Belgium, the Ustaše in Croatia, et alii.

Before the Second World War, fascists considered they shared common philosophic tenets — the Leader, Single-party State, Social Darwinism, élitism, yet each government espoused a discrete variety of national fascism, e.g. the Portuguese clerico–corporativist Estado Novo (New State) of the António de Oliveira Salazar régime; and the Spanish alliance among Falangists, Clerical Fascists, and Generalissimo Franco. In 1945, at War’s end, upon the Allied vanquishing of Nazi Germany (1933–45) most fascist governments dissociated themselves from Nazism — lest their national variety be equated with the Hitlerian (1933–45) variety of fascism.