S12, S.XII, S-12 or S.12 may refer to: In military * SABCA S-12, a Belgian aircraft * SIAI S.12, an Italian 1910s reconnaissance flying-boat * SPAD S.XII, a French single-seat biplane fighter aircraft of the First World War * USS S-12 (SS-117), a 1921 S-class submarine of the United States Navy * Saiga-12, a Russian semi-automatic shotgunIn transportation * , pertaining to the 1984-88 Nissan Silvia/200SX * S12 postcode, covering areas of south eastern Sheffield * Baldwin S-12, a 1951 1,200 horsepower (890 kW) diesel-electric locomotive * Rans S-12 Airaile, ultralight aircraftRoads * S12 (ZVV), a S-Bahn line in the cantons of Zürich and Zug in Switzerland * County Route S12 (California), a road in California * Expressway S12 (Poland) * Airport Expressway (Beijing)In science and