Also found in: Wikipedia.
a mountain pass in the Styrian Alps in eastern Austria, leading from the Mürz River valley to the valley of the Schwarza River (a tributary of the Leitha River). Elevation, 985 m. A highway has been built through the Semmering Pass. The oldest railroad in the Alps, built from 1842 to 1854, travels through a tunnel (length, approximately 1.5 km) under the pass and connects Vienna and Graz. The Semmering region is a well-known health resort.