SMN may refer to: Lemhi County Airport, IATA airport code of SMN Netherland Line (Stoomvaart Maatschappij Nederland) Seri Maharaja Mangku Negara, a Malaysian honour S-m-n theorem, a computability theorem regarding programming languages Servicio Meteorológico Nacional (Mexico), Mexico's National Meteorological Service Servicio Militar Nacional, Mexico's National Military Service Société Métallurgique de Normandie, a steel mill in Caen, Normandy, France Stathmin protein Satellite Music Networks, a US radio network Inari Sámi language Survival of motor neuron protein, a protein complex