Breton (/ˈbrɛtən/, BRET-ən; French: [bʁətɔ̃]; endonym: brezhoneg [bʁeˈzɔ̃ːnɛk] or [bɾəhɔ̃ˈnek] in Morbihan) is a Southwestern Brittonic language of the Celtic language group spoken in Brittany, part of modern-day France. It is the only Celtic language still in use on the European mainland.
Breton is an Insular Celtic language that was brought from Great Britain to Brittany by migrating Britons during the Early Middle Ages, making Breton most closely related to Cornish, another Southwestern Brittonic language. Welsh and the extinct Cumbric, both Western Brittonic languages, are more distantly related, and the Goidelic languages (Irish, Manx, Scottish Gaelic) have a slight connection due to both of their origins being from Insular Celtic.