What is "gontia"

Gontia was a Celtic goddess. She was the tutelary deity of the river Günz, near Günzburg in Germany. She is known from an inscription on a Roman-era altar at Günzburg that reads Gontiae / sac(rum) / G(aius!) Iulius / Faventianus / |(centurio) leg(ionis) I Ital(icae), or ‘Gaius Julius Faventianus, centurion of the Legio I Italica, (made) this offering to Gontia’.

She also appears to be connected with the Belgian city Ghent.