Breton (, 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, which makes 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, and Scottish Gaelic) have a slight connection due to their origins being from Insular Celtic. Having declined from more than one million speakers around 1950 to 107,000 in 2024, Breton is classified as "severely endangered" by the UNESCO Atlas of the World's Languages in Danger. Yet, the number of children attending bilingual classes rose 33% between 2006 and 2012 to 14,709.