Os is a municipality in Innlandet county, Norway. It is located in the traditional district of Østerdalen. The administrative centre of the mun…Os is a municipality in Innlandet county, Norway. It is located in the traditional district of Østerdalen. The administrative centre of the municipality is the village of Os i Østerdalen. Other villages in the municipality include Dalsbygda, Narbuvoll, and Tufsingdalen.