Foix, a town of S. France, capital of the department of Ariege, on the left bank of the river Ariege at its junction with the Arget, in a narrow valley at the foot of the Pyrenees, 404 m. S. of Paris, and 43 m. S. by E. of Toulouse, with which it is connected by rail; pop. in 1866, 6,746. It has considerable trade and various manufactures, the principal of which is iron. It was founded probably about the 2d century, and in the 11th century became the capital of a county, and was a stronghold of importance. The county of Foix nearly corresponded to the department of Ariege.