Of or relating to any of the Brittonic languages spoken by the Celtic inhabitants of Britain. Later: spec. Welsh; (occasionally) Cornish.

(a) n. any of the Celtic languages spoken in early Britain or their modern descendants; (later) spec. those of the P-Celtic group (= Brittonic, n.)…

Of or relating to the group of Celtic languages in which the Indo-European voiceless labiovelar stop (the sound typically represented in modern…