Benelux is the region of Europe comprising Belgium, the Netherlands, and Luxembourg. The name is formed from the beginning of each country's name, and was created for the Benelux Economic Union, but is now used in a more generic way.
The Benelux Economic Union (Benelux Economische Unie/Union Économique Benelux) was signed in 1944 and came into force in 1948 to promote the free movement of workers, capital, services, and goods in the region. Its founding contributed to the founding of the European Union (EU), though the immediate precusors to the EU were founded later (the ECSC in 1951 and the EEC in 1957). The three countries were also founding members of these organisations, together with West Germany, France, and Italy.