a market-town of Wales, in the county of Caernarthen, is pleasantly situated on the banks of the Teifi, 16 miles N.W. by N. of Caernarthen, and 229 W. by N. of London. It was anciently called Dinas-Emlyn, or the "City of Emlyn," and a castle existed here at a very early period. It was rebuilt in the time of Henry VII. by Sir Rhys-ap-Thomas, and the place then obtained the name of Newcastle. The castle was held by the royalists during the civil war, but after that period it gradually fell into decay, and only the ruins now remain. The town is well built, and contains an Episcopal, a Baptist, and other churches; a school; and a savings-bank. Some trade is carried on in cattle, for which there are eleven yearly fairs. Newcastle-Emlyn is included in the parish of Kenarth, which had in 1851 a population of 1980.