What is the X in X-mas?
1630s, "covered chair on poles," possibly from a southern Italian dialect derivative of Italian sede "chair" (cf. Italian seggietta, 1590s; the thing itself was said to have been introduced from Naples), from Latin sedes, related to sedere "sit" (see sedentary). Since Johnson's conjecture, often derived from the town of Sedan in France, where it was said to have been made or first used, but historical evidence for this is lacking.
Introduced in England by Sir Sanders Duncombe in 1634 and first called a covered chair. "In Paris the sedan-chair man was usually an Auvergnat, in London an Irishman" ["Encyclopaedia Britannica," 1929]. Meaning "closed automobile seating four or more" first recorded 1912, American English.
town, Ardennes departement, Champagne-Ardenne region, northeastern France. Sedan is situated 9 miles (14 km) southwest of the Belgian frontier. It lies on the right bank of the Meuse River along a loop in the river in a depression between two ridges. Most of the 17th- and 18th-century houses in the centre of the town were destroyed during the German invasion of France in 1940 during World War II. The 15th-century castle is locally claimed to be the largest in Europe. A statue has been erected in the centre of the town to Marshal Henri de la Tour d'Auvergne, vicomte de Turenne, the famous 17th-century French soldier, who was born in the chateau of the stronghold.