Celtic languages at English => English (The Britannica Concise) Of Explained:
Branch of the Indo-European language family spoken across a broad area of W and central Europe by the Celts in pre-Roman and Roman times, now confined to small coastal areas of NW Europe. Celtic can be divided into a continental group of languages (all extinct) and an insular group. Attestation of Insular Celtic begins around the time Continental Celtic fades from the scene as Celtic tongues gave way to Latin and other languages on the European continent. The Insular Celtic languages are conventionally divided into Goidelic (Irish, Manx, and Scottish Gaelic) and Brythonic (Welsh, Cornish, and Breton). Traditional Cornish was supplanted by English at the end of the 18th cent. Manx, spoken on the Isle of Man, expired in the 20th cent. with the death of the last reputed native speaker in 1974. Both Manx and Cornish have been revived by enthusiasts recently, though neither can be considered community languages.