The Adige (Italian: [ˈaːdidʒe]; German: Etsch [ɛtʃ] (listen); Venetian: Àdexe [ˈadeze]; Romansh: Adisch [ɐˈdiːʃ] (listen); Ladin: Adesc; Latin: Athesis; Ancient Greek: Ἄθεσις, romanized: Áthesis, or Ἄταγις, Átagis) is the second-longest river in Italy, after the Po. It rises near the Reschen Pass in the Vinschgau in the province of South Tyrol, near the Italian border with Austria and Switzerland, and flows 410 kilometres (250 mi) through most of northeastern Italy to the Adriatic Sea.

The name of the river is of unknown origin. Nineteenth-century theories, such as a derivation from the Proto-Celtic *yt-ese, "the water", and alleged to be cognate with the River Tees in England (anciently Athesis, Teesa), have never been accepted by Celtic onomasts, and are now completely obsolete.