what is sn
1 SavinâNorov machine gun. 2  Space Network, a NASA relay satellite system. 3  Sthene, an obsolete unit of force or thrust in the metre-tonne-second system of units. 4  Substantia nigra, a brain structure. 5  Supernova, a stellar explosion, in astronomy and cosmology.  Tin, a metallic element with chemical symbol Sn.