TRENTINO–ALTO ADIGE, autonomous, bi-lingual region of northern Italy whose two constituent parts, the Italian-speaking Trentino in the south and the German-speaking Alto Adige or Süd-Tirol (South Tyrol) in the north reflect post-World War One boundary re-drawing whereby Süd-Tirol was ceded to Italy from what is now Austria. The main river traversing the region, the Adige (Italian-speaking) or Etsch (German-speaking) is fed by Alpine snowmelt.