Clydau (sometimes Clydaï or Clydey) is a village, parish, and community in the Hundred of Cilgerran in Pembrokeshire, Wales. The village is a small group of houses around the parish church, 8 km southwest of Newcastle Emlyn and 13 km southeast of Cardigan. Although the village is tiny, the parish is large, encompassing several larger hamlets, the village of Tegryn, and a large number of scattered farms. The community consists essentially of the parishes of Clydey and West Cilrhedyn (3 km to the east: church at ).
The meaning of the Welsh placename is uncertain, although the church is now dedicated to Ste. Clydaï, an alleged daughter of Brychan. During the early middle ages, the present town was the site of Llangeneu ('St Ceneus'), which was accounted one of the seven principal sees of Dyfed despite having no endowment of land.
The River Cneifa, a tributary of Afon Cych, divides the parish into two ancient divisions: Uwchlawrllan to the southeast and Islawrllan to the northwest. A remote upland area with no classified roads, the community is a bastion of the Welsh language.
Census population of community 1100 (1801): 1457 (1851): 1057 (1901): 829 (1951): 681 (2001). The percentage of Welsh speakers was: 99 (1891); 97 (1931); 91 (1971).
- Charles, B. G., The Placenames of Pembrokeshire, National Library of Wales, Aberystwyth, 1992, ISBN 0-907158-58-7, p 678
- James, Heather. "The Geography of the Cult of St Davids" in St David of Wales: Cult, Church and Nation, p. 59. Boydell Press, 2007. Accessed 26 Mar 2013.
- Wade-Evans, Arthur. Welsh Medieval Law, p. 263.