1 Latin name for the British kingdom in Brittany (Armorica), established in the 5th century ad. One of three kingdoms, along with Cornouaille and Bro Waroch, Domnonia covered most of northern Brittany, including, after 530, the province of Leon in the north-west. Its relationship with the British province of Dumnonia (Devon and Cornwall) is not certain. A portion of this kingdom became the pre-Napoleonic county of Domnonée. Today it embraces the Departments of Côtes d'Armor and Finistère north of the River Élorn.
2 (of south-western Britain). See DUMNONIA.