The Basque señoríos were medieval hereditary land titles over an area called señorío ( Lordship ), recognized by a king to former basque chieftains in relation to the concept of manorialism in exchange for sworn allegiance. The Basque term is jaurerria (pronounced [xauˈɾeria]), means "lord's country" and usually relates to the señoríos of the Basque Country. Either term frequently refers to the most important of these, the Bizkaiko Jaurerria or Señorío de Vizcaya (Lordship of Biscay) as it is known in Spanish. Most other Basque jauerriak were much smaller, such as the Oñatiko Jaurerria (Señorío de Oñate).

This title conferred considerable powers into the hands of the Lord of Vizcaya which in other area were directly controlled by the king. A señor was the judicial and military high authority, was entitled to rule directly without referring to the king, had the power to appoint civil servants and was entitled to collect taxes.

After the Sancho III of Navarre annexed Castile in 1029, the titles to the Lordship of Biscay were granted by the Kings of Navarre. This early "core" of Biscay consisted of:

The Basques (Basque: euskaldunak, Spanish: vascos, French: basques) as an ethnic group, primarily inhabit an area traditionally known as the Basque Country (Basque: Euskal Herria), a region that is located around the western end of the Pyrenees on the coast of the Bay of Biscay and straddles parts of north-central Spain and south-western France.

The Basques are known in the local languages as:

The English word Basque comes from French Basque (pronounced /bask/), which itself comes from Gascon Basco (pronounced /ˈbasku/) and Spanish Vasco^{[citation needed]} (pronounced /ˈbasko/). These, in turn, come from Latin Vasco (pronounced /wasko/), plural Vascones (see History section below). The Latin labial-velar approximant /w/ generally evolved into the bilabials /b/ and /β̞/ in Gascon and Spanish, probably under the influence of Basque and Aquitanian, a language related to old Basque and spoken in Gascony in Antiquity (similarly the Latin /w/ evolved into /v/ in French, Italian and other languages).