county name, Old English Defena(scir) "(territory of the) Dumnonii," a Celtic people-name. As a type of cattle, from 1798.
Entries linking to devon
Devonian adj.
1610s, "of or pertaining to Devonshire;" see Devon + -ian. The earlier adjective was Devonish (early 14c.). In reference to a geological era, 1837, applied by Murchison, because the formations of that age are prominent in the county, where they first were studied.