Cardigan (Welsh, Aberteifi), town, in Ceredigion, on the River Teifi in south-western Wales. Cardigan grew up around a Norman castle beside the river. During the English Civil War, the castle fell to Parliamentarians in 1645. Also there is an ancient stone bridge across the Teifi which dates from the 12th century. Cardigan is a market town for produce, mainly sheep, dairy products, and potatoes, from the surrounding agricultural area. Population 3,758 (1991).