The Semois is a river flowing from the Ardennes

Ardennes

The Ardennes is a region of extensive forests, rolling hills and ridges formed within the Givetian Ardennes mountain range, primarily in Belgium and Luxembourg, but stretching into France , and geologically into the Eifel...

 uplands of Belgium

Belgium

Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

 and France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 towards the River Meuse

Meuse River

The Maas or Meuse is a major European river, rising in France and flowing through Belgium and the Netherlands before draining into the North Sea...

, of which it is a right tributary.

The source of the Semois is in Arlon, in the Belgian province of Luxembourg, close to the border with the Grand Duchy of Luxembourg

Luxembourg

Luxembourg , officially the Grand Duchy of Luxembourg , is a landlocked country in western Europe, bordered by Belgium, France, and Germany. It has two principal regions: the Oesling in the North as part of the Ardennes massif, and the Gutland in the south...

. Flowing in a roughly westerly direction, it enters France after passing through the Belgian village of Bohan-sur-Semois

Bohan sur Semois

Bohan sur Semois is a village located in Belgium. It is found in the Belgian Ardennes mountains on the banks of the Semois river. It is located in the province of Namur in the French speaking part of Belgium, Wallonia. Bohan is only 2 km from the French border.The micro-climatic conditions in...

 and joins the Meuse some 10 km further downstream in Monthermé

Monthermé

Monthermé is a commune in the Ardennes department in northern France.-Population:-References:*...

. The total length of the river is 210 km.

Other places on the banks of the Semois are Chiny

Chiny

Chiny is a Walloon municipality of Belgium located in the province of Luxembourg.On 1 January 2007 the municipality, which covers , had 5,021 inhabitants, giving a population density of 44.2 inhabitants per km²...

, Florenville

Florenville

Florenville is a Walloon municipality located in the Belgian province of Luxembourg. On 1 January 2007 the municipality had 5,448 inhabitants. The total area is 146.91 km², giving a population density of 37.1 inhabitants per km²....

, Herbeumont

Herbeumont

Herbeumont is a Walloon municipality of Belgium located in the province of Luxembourg.On 1 January 2007 the municipality, which covers 58.81 km², had 1,536 inhabitants, giving a population density of 26.1 inhabitants per km².- Escape Dutroux :...

, Bouillon

Bouillon

Bouillon is a municipality in Belgium. It lies in the country's Walloon Region and Luxembourg Province.The municipality, which covers 149.09 km², had 5,477 inhabitants, giving a population density of 36.7 inhabitants per km².- History :...

 (including the localities of Dohan

Dohan

Dohan. sometimes known as Dohan-sur-Semois, is a small village belonging to the municipality of Bouillon in the Belgian province of Luxembourg...

 and Poupehan), and Vresse-sur-Semois

Vresse-sur-Semois

Vresse-sur-Semois is a Walloon municipality of Belgium located in the province of Namur. It consists of the former municipalities of Alle, Bagimont, Bohan, Chairière, Laforêt, Membre, Mouzaive, Nafraiture, Orchimont, Pussemange, Sugny and Vresse....

(all in Belgium).

The earliest documentation of the name, as SESMARA, is dated from the 2nd century AD. That was before that region was influenced by significant Germanic immigration. Medieval forms include Sesomirs (664), Sesmarus (950), Sesmoys (1104), and Semoir (1244).

The river has given its name to a variety of tobacco grown in the area.