any of the Italian patriots prominent in the last quarter of the 19th century and the early 20th century who sought to deliver Italian lands from foreign rule. Their name was derived from the words Italia irredenta (“unredeemed Italy”), and their object was to emancipate the lands of Trentino (south Tirol), Gorizia, Istria, Trieste, Ticino, Nice, Corsica, and Malta from Austrian, Swiss, French, and British rule.

The Irredentists aimed especially at gaining several Italian-inhabited areas still controlled by Austria after the process of Italian unification (1860–70). In the last two decades of the 19th century, they opposed Italy's adherence to the Triple Alliance, which included Austria. The Irredentists contributed to the pressure that caused the Italian government to enter World War I on the side of the Allies (May 1915). Italy's acquisition of the Istrian (Istria) peninsula on the north Adriatic and of south Tirol from Austria after the war fulfilled the hopes of many of the Irredentists.