a federal kingdom in NW Europe: at various times under the rulers of Burgundy, Spain, Austria, France, and the Netherlands before becoming an independent kingdom in 1830. It formed the Benelux customs union with the Netherlands and Luxembourg in 1948 and was a founder member of the Common Market, now the European Union. It consists chiefly of a low-lying region of sand, woods, and heath (the Campine) in the north and west, and a fertile undulating central plain rising to the Ardennes Mountains in the southeast. Languages: French, Flemish (Dutch), German. Religion: Roman Catholic majority. Currency: euro. Capital: Brussels. Pop: 11 429 336 (2017 est). Area: 30 513 sq km (11 778 sq miles)