Trelleborg (trĕləbôrˈyə) [key], city (1990 pop. 22,850), Malmöhus co., extreme S Sweden, a port on the Baltic Sea. Manufactures include machinery, rubber, cement, and refined sugar. It is an important crossing point to continental Europe, with ferry connections to Germany. Trelleborg was founded in the Middle Ages and owed its early prosperity to abundant herring catches in the Baltic. Its modern growth dates from the late 19th cent. The name is sometimes spelled Trälleborg.