Cornouaille is an historic region in Brittany, in northwest France. "Les ," however, is the French for Cornwall in Great Britain.There is a chance that the name Cornouaille was given in relation to the region of the British Isles. (This happened for Devon, formerly called Dumnonia in Latin: la Domnonée becoming the name of the equiavlent region in France in the early middle-ages.)

The original germanic name signfies "The corner of foreigners" in reference to the resettling of the Celts from over the English Channel by the Danish invaders.

The region was first mentioned by this name between 852 and 857 when the Bishop of , Anaweten, took over 'Cornugallensis'.

The existence of a district of ancient Anjou called "La Cornuaille" has led to the hypothesis that it was a geographical or military label for all of southern Brittany as far as the northern shore of la Domonée in the 6th or 7th century.

At the origin of this feudal county, the reigning dynasty acceded to a dukedom of the region, which then passed to the bishop of Quimper.

The nameCornouaille signifies the diocese of Quimper which persisted until the French Revolution. The diocese covered more than half of the south of Finistère, and extended over part of Morbihan and the Côtes-d'Armor. There were two arch-deacons, one for Cornouaille and one for Poher . There were also a cantor, a treasurer, a theologian and twelve canons. This episcopal division was the poorest in Brittany.

After the French Revolution, the new constitution created a diocese of Finistère, erasing that of Cournouaille; most of the old diocese was absorbed into the new.

In Breton, the region is known as "Kerne", and in Latin "Cornugallia."

The name Cornouaille is not to be confused with the French word Cornouailles referring to Cornwall in southwest Britain.