The Sinni (Latin: Siris or Semnus; Greek: or ) is a 94 km long river in the Basilicata region of southern Italy. In antiquity, the city of Siris lay at its mouth. Near the town of Senise, a dam on the river was built in 1970-1982, the largest in Europe built with earth. In correspondence of it, it forms the , one of the largest artificial basins in Italy.
