Geoagiu is a town in Hunedoara County, Romania, located on the Mureş river at an altitude of 217 meters over the sea level. The river with the same name (Geoagiu) flows in this place into the Mureş. The town has a population of about 6,500.
The first settlements in the area can be found in the time of the Dacians, in the 1st century BC, as shown by archeological discoveries. After the Roman conquest, the Romans the fort of Germinsana in the 2nd century, however, it kept the original Dacian name.
The name of Germisana meant "hot water" (germi = "heat", sara = "waterfall") and it showed that the Dacians already knew of the thermal springs of the area. Another opinion that the name came from the Hungarian name of the river Gyógy which means "curative". But more probably, the name is coming from the Hungarian word dió (nut as fruit) with the suffix -d, so, after the first documentary citation, "villa Gyog" from 1291 appeared as Dyod és Dyog (1397), Aldyogh (1407), Algyogh (1412), Aldyod (1439), Alsodyod alio nomine Alsoffalwa (around 1444).
The first documentary citation of Geoagiu (it was written as "villa Gyog") was in the year 1291, when it was used as a land in the vicinity of Bintinti (now the village Aurel Vlaicu).