Cornish (adj.)

"of or pertaining to Cornwall," the county in the far southwest of England, late 14c. (as a surname), from first element of Cornwall (q.v.) + -ish. Earlier was Cornwalsche, Cornwalish (c. 1200). As a noun, the name of the ancient Celtic language of Cornwall, extinct as a spoken language since late 18c., from 1540s. Related: Cornishman.