The place-names of Wales derive in most cases from the Welsh language, but have also been influenced by linguistic contact with the Romans, Anglo-Saxons, Vikings, Anglo-Normans and modern English. Toponymy in Wales reveals significant features of the country's history and geography, as well as the development of the Welsh language. Its study is promoted by the Welsh Place-Name Society.

Llantwit Major is a town and community in Wales on the Bristol Channel coast. It is one of four towns in the Vale of Glamorgan, with the third largest population after Barry and Penarth, and ahead of Cowbridge. It is 4+1⁄2 miles (7.2 km) from Cowbridge, 9 miles (14 km) from Bridgend, 10 miles (16 km) from Barry, and 15 miles (24 km) from Cardiff. It had a population of 9,530 in 2021.