a town of Somersetshire in England, seated on the river Yeo, 129 miles from London, is so called, because it once had a castle, and stands on the river Ivel. It is a place of great antiquity, as appears by the Roman coins which are sometimes dug up. It is likewise evident, from the ruins and from two towers on the bridge, that it was once a large place, and encompassed with a double wall. It also had several parish churches, though now but one. It is governed by two bailiffs, who with the twelve burgesses are lords of the manor. In the reign of Edward III., the assizes for the county were fixed here, which have since been held alternately at Wells, Taunton, and Bridgewater. The knights of the shire are always chosen here, and it is the place for the county courts and jail. On the latter is its chief dependence, and therefore it cannot be very polite. It is noted for being the birth-place of Roger the famous Friar Bacon. Ilchester is an earldom in the Fox family.