SIENNESE, a duchy in Italy; bounded on the north by the Florentine, on the south by the Mediterranean sea and the duchy of Castro, on the east by the Perugino and Orvietano, and on the west by the Florentine and the Tuscan sea; being about 55 miles in length, and as much in breadth. The soil is pretty fertile, especially in mulberry trees, which feed a great number of silk-worms; and there are several mineral springs. Siena is the capital town.