ABERYSTWITH, a market-town of Cardigan-shire, in Wales, seated on the Ridal, near its confluence with the Ilwirth, where it falls into the sea. It is a populous, rich town, and has a great trade in lead, and a considerable fishery of whiting, cod, and herrings. It was formerly surrounded with walls, and fortified with a castle; but both are now in ruins. Its distance from London is 203 miles W. N. W. W. Long. 4. 15. N. Lat. 52. 30.