West Wales (Welsh: Gorllewin Cymru) is not clearly defined as a particular region of Wales. Some definitions of West Wales include only Pembrokeshire, Ceredigion and Carmarthenshire, which historically comprised the Welsh principality of Deheubarth:87, 95 and was called "South West Wales" in the Nomenclature of Territorial Units for Statistics (NUTS). Other definitions include Swansea and Neath Port Talbot but exclude Ceredigion. The "West Wales and the Valleys" NUTS area includes more westerly parts of North Wales.
Historically, the term West Wales was applied to the Kingdom of Cornwall during the Anglo-Saxon invasion of Britain and the period of the Heptarchy. The Old English word Wealas, a Germanic term for inhabitants of the Western Roman Empire, which the Anglo-Saxons came to apply especially to the Britons, gave its name to Wales and is also the origin of the second syllable in the name Cornwall.