one of two groups of the modern Celtic languages, the other being Goidelic. The Brythonic languages (from Welsh (Welsh language) brython, “Briton”) are or were spoken on the island of Great Britain and consist of Welsh, Cornish (Cornish language), and Breton (Breton language). They are distinguished from the Goidelic (Goidelic languages) group by the presence of the sound p where Goidelic has k (spelled c, earlier q), both derived from an ancestral form *k^w in the Indo-European parent language. (An asterisk identifies a sound as a hypothetical and reconstructed form.) The Brythonic languages are therefore sometimes referred to as P-Celtic.