The Celtic or Keltic languages (usually pronounced /ˈkɛltɪk/ but sometimes /ˈsɛltɪk/)^[1] are descended from Proto-Celtic, or "Common Celtic"; a branch of the greater Indo-European language family. The term "Celtic" was first used to describe this language group by Edward Lhuyd in 1707.^[2]

Celtic languages are most commonly spoken on the north-western edge of Europe, notably in Ireland, Scotland, Wales, Brittany, Cornwall, and the Isle of Man, and can be found spoken on Cape Breton Island. There are also a substantial number of Welsh speakers in the Patagonia area of Argentina. Some people speak Celtic languages in the other Celtic diaspora areas of the United States,^[3] Canada, Australia,^[4] and New Zealand.^[5] In all these areas, the Celtic languages are now only spoken by minorities though there are continuing efforts at revitalization.

During the 1st millennium BC, they were spoken across Europe, in the Iberian Peninsula, from the Atlantic and North Sea coastlines, up the Rhine valley and down the Danube valley to the Black Sea, the Upper Balkan Peninsula, and in Galatia in Asia Minor. The spread to Cape Breton and Patagonia occurred in modern times. Celtic languages were spoken in Australia before federation in 1901.

Living languages[link]

SIL Ethnologue lists six "living" Celtic languages, of which four have retained a substantial number of native speakers. These are Irish and Scottish Gaelic (descended from Old Irish), Welsh, and Breton, descended from the British language.

The other two, Cornish and Manx, were spoken into modern times but later died as spoken community languages.^[6][7][8] For both these languages, however, revitalization movements have led to the adoption of these languages by adults and children and produced some native speakers.^[9][10]

Taken together, there were roughly one million native speakers of Celtic languages as of the 2000s.^[11] In 2010, there were more than 1.4 million speakers of Celtic languages.^[12]

Demographics[link]