Cohors tertia Aquitanorum equitata civium Romanorum ("3rd part-mounted Cohort of Aquitani Roman citizens") was a Roman auxiliary mixed infantry and cavalry regiment. It may have been originally raised in Gallia Aquitania in the reign of founder-emperor Augustus after the revolt of the Aquitani was suppressed in 26 BC. Alternatively, it may have been raised by emperor Claudius (r. 41-54) to replace regiments stationed in the newly annexed province of Britannia. Unlike most Gauls, the Aquitani were not Celtic-speaking but spoke Aquitanian, a now extinct non Indo-European language closely related to Basque.