a town of France, capital of an arrondissement in the department of Morbihan, on the left bank of the Blavet, 30 miles N. by W. of Vannes. It is ancient, and has still some remains of the old walls and gates. A new quarter was added by Napoleon I., who gave the town the name of Napoleonville. On the restoration of the Bourbons the old name was resumed; but recently it has again been called Napoleonville, and is given under that name in the census of 1856. The chief building in the town is the picturesque but ruinous old castle of the dukes of Rohan. The new portion lies outside the walls, and has broad regular streets; but being unfinished, it has a desolate appearance. Pontivy has a prison and very handsome cavalry barracks. It contains numerous tanneries, and has an active trade in corn, linen, thread, horses, cattle, hides, leather, &c. Pop. (1856) 6859.