According to Greek mythology, the word Hellenes originated from Hellen, son of Deucalion and Pyrrha, who had three sons, Aeolus, Dorus and Xuthus. Aeolus, Dorus and the sons of Xuthus, Achaen and Ion, were the predecessors of the four primary tribes of Greece, the Aeolians, the Dorians, the Achaeans and the Ionians.
Another theory is that the origin of the word Hellen is the name of the priests of Zeus in Dodona, a Greek tribe in Epirus, Selloi, which means lighten.
The word Graikos (lat. Graeci) is the origin of the word Greek. In an inscription dating back to the 4th century B.C., those who were called Graeci named themselves Greeks, as Aristotle also indicated in one of his works.
Rhoman, Rhomaios or Romios is the name by which Greeks were known in the Middle Ages and during the Ottoman rule. The term Rhomaios came to represent the hellenized inhabitants of the East Roman Empire and had a more political than national meaning.
A different term came to establish itself in the East. The ancient people of the Middle East referred to Hellenes as Yunan, deriving from Persian Yauna which originates from Ionia, the western coast of Asia Minor.
The related name Yavan or Javan was used to refer to the Greek nation in the Eastern Mediterranean in early biblical times.
There are more theories about the origins of these words and their definitions changed over the years. Nowadays the official name of Greece in the European Union is Hellas.