Senis is a comune (municipality) in the Province of Oristano in the Italian region Sardinia, located about 70 kilometres (43 mi) north of Cagliari, and about 30 kilometres (19 mi) southeast of Oristano. As of 31 December 2004, it had a population of 546 and an area of 16.0 square kilometres (6.2 sq mi).[3]