a district in the east of the province of Salamanca in Spain, with an agricultural population of 14,162. Its chief town of the same name gave their title to the Dukes of Alva. The remains of their once magnificent castle stand on an eminence near the town, overlooking the plain of the Tormes. Pop. 2176. Here the French, under Kellermann, defeated the Spaniards, Nov. 26. 1809.