USK, a market-town in the hundred of the same name, in the county of Monmouth, 144 miles from London. It takes the name of the river on which it is built. On a hill near it are the ruins of its ancient castle. The church is of Norman construction, built in the form of a cathedral. The priory, to which it appertained, is now in ruins. Usk is a borough, and, in conjunction with Monmouth and Newport, returns one member to the House of Commons. A market is held on Monday. The population amounted in 1821 to 959, and in 1831 to 1160.