Arausio was a local Celtic

Celtic polytheism

Celtic polytheism, commonly known as Celtic paganism, refers to the religious beliefs and practices adhered to by the Iron Age peoples of Western Europe now known as the Celts, roughly between 500 BCE and 500 CE, spanning the La Tène period and the Roman era, and in the case of the Insular Celts...

 water god who gave his name to the town of Arausio (Orange

Orange, Vaucluse

Orange is a commune in the Vaucluse department in the Provence-Alpes-Côte d'Azur region in southeastern France.It has a primarily agricultural economy...

) in southern Gaul

Gaul

Gaul was a region of Western Europe during the Iron Age and Roman era, encompassing present day France, Luxembourg and Belgium, most of Switzerland, the western part of Northern Italy, as well as the parts of the Netherlands and Germany on the left bank of the Rhine. The Gauls were the speakers of...

.

Inscriptions attest to the presence of this presiding deity who gave the town its name.
The modern name Orange is a corrupted version of celtic word Arausio - the effect is that with the celtic language and beliefs fading away the sound and spelling of the name migrated (in steps) toward an existing latin/Romance word .. Orange.