Ancient/Iron Age Tribal names....Latin or Local.

[Ariovistus]

"In the history of Rome, the Latin term civitas (plural civitates), according to Cicero in the time of the late Roman Republic, was the social body of the cives, or citizens, united by law (concilium coetusque hominum jure sociati)."

This may shed some light onto the name "Civitas". Calleva most likely became the capital for the military province when it was annexed around 44 AD, hence the change to Civitas.