The Aquitanian language was the language of the ancient Aquitani, a people living in Roman times between the Pyrenees, the Garonne river and the Atlantic Ocean. Epigraphic evidence for this language has also been found south of the Pyrenees, in Navarre and Castile.
There is no surviving text written in Aquitanian. The only evidence comes from onomastic data (roughly 200 personal names and about 60 deity names) that have survived indirectly in Latin inscriptions from the Roman imperial period, primarily between the 1st and 3rd centuries AD, with a few possibly dating to the 4th or 5th centuries. The Gascon language has a substrate from Aquitanian, with certain words related to Basque.
The consensus among scholars is that Aquitanian was a Paleo-European language genetically related to Basque, though there is debate over the exact nature of their relationship. Some linguists, like R. L. Trask, argue that it was a near-direct ancestor of Basque, while others, including Lyle Campbell, suggest that it may have been a close relative of Basque rather than its direct ancestor.
Aquitanian is attested only in the form of proper names, and we lack enough data to determine their exact meanings. For instance, the Aquitanian words andere, umme, and sahar are interpreted as 'woman, lady', 'child', and 'old', respectively, by comparison with the Basque words andere, ume, and zahar.
According to linguist José Ignacio Hualde, since Aquitanian was spoken over a vast area (some names of Aquitanian origin have been found as far south as Soria in Castile), it likely featured several dialects. He suggests that Basque may have evolved from one of these dialects, though it remains unclear which Aquitanian names belong to Basque's direct ancestor and which come from a related sister dialect. Hualde refers to the reconstructed common ancestor of Proto-Basque and the other Aquitanian dialects as 'Proto-Basque-Aquitanian'.
Drawing on linguistic evidence, JoaquÃÂn Gorrochategui concludes that the Aquitanian language was spoken in ancient times (from at least the 1st century BC until the end of the Roman Empire) across a region stretching from Biscay in the west to the Aran Valley in the east, and from the Aquitanian Plain in the north down to the Ebro river in the south.
The Aquitanian language came into contact with Gaulish around Tolosa (Toulouse) and the Garonne river, and with Celtiberian further west and around the Ebro river. Both of these languages penetrated Aquitanian-speaking territory, leaving evidence in personal names and place names.
Most Aquitanian onomastic elements are clearly identifiable from a Basque perspective, matching closely the forms reconstructed by the linguist Koldo Mitxelena for Proto-Basque: