Basque dialects are linguistic varieties of the Basque language which differ in pronunciation, vocabulary and grammar from each other and from Standard Basque. Between 6 and 9 Basque dialects have been historically distinguished:
- Upper Navarrese (Northern and Southern)
- Lower Navarrese (Eastern and Western)
- Souletin (Souletin and Roncalese)
In modern times, though, both Upper Navarrese and Lapurdian are considered part of the Navarrese–Lapurdian dialect, so the dialects would be five, divided in 11 subdialects, their minor varieties being 24.
The boundaries of all these dialects do not coincide directly with current political or administrative boundaries. It was believed that the dialect boundaries between Bizkaian, Gipuzkoan and Upper Navarrese did show some relation to some pre-Roman tribal boundaries between the Caristii, Varduli and Vascones. But, nowadays, the main Basque dialectologists deny any direct relation between those tribes and Basque dialects. Looking at historical evidences, it seems that these dialects were created in the Middle Ages from a previously quite unified Basque language, and that the dialects diverged from each other since then due to the administrative and political division that happened in the Basque Country.