(formerly Ivelchester, from the River Ivel or Yeo, on which it stands), a market-town of Somersetshire, 33 miles S.S.W. of Bath. Under the Romans it was an important military station, and bore the name of Ischalis. Traces of its fortifications may still be seen, and numerous coins, urns, &c., have been discovered. It formerly returned two members to Parliament, but was disfranchised by the Reform Act. Ilchester was the birth-place of Roger Bacon.