The term Berber is a variation of the Latin original word Barbarian, earlier in history applied by Romans specifically to their northern hostile neighbors from Germania (modern Germany) and to the hostile Berbers of North Africa. The variation is a French one when spelled Berbere and English when spelled Berber. The term appeared first in the 4th century in the religious conflicts between Saint Augustine, a Numidian Berber-Roman bishop of the Catholic faith, and the Donatist allies of the Barbarians, also known as Vandals. The Vandals migrated from Iberia (modern Spain and Portugal) where they were assailed by the Gauls allied to the Romans, and settled west of the Roman city of Carthage (in modern Tunisia) in the highlands (in modern Algeria).
The Greek term "βάρβαρος / βάρβαροι" was originally a derogatory term for all non-Greek speakers. The nonsense syllables "bar-bar" have no meaning in Greek; the term implied that all languages other than Greek were a collection of nonsense syllables. The term has been variously translated as "stutterers," "stammerers," or "babblers." But the term did include, from the beginning, a connotation of being non-civilized or "barbaric" that later became primary in cognate terms like "barbarian."
Contrary to some sources, the Berbers/Imazighen (the Berber people) were probably not called barbarians by the Greeks. The Berbers were known as Libyans (Λίβυες or Λίβυοι) or Mazyes (Μάζυες or Μάξυες; Mazaces in Latin) to the ancient Greeks. They were known under many other names to the Romans as Numidians, Mauri and Moors. The Egyptians called their western neighbors the Mashewsh.
Because the Berbers were called Al-Barbar by the Arabs, it is possible that the modern European languages and other ones adopted it from the Arabic language, which in turn possibly adopted it from the Greek language or from Latin. The Arabs probably did not use the name Al-Barbar mainly as a derogatory name, as they possibly borrowed it from other languages. The ancient Arab-Muslim historians were not aware of the origin of that name, they cited some myths or stories about the name. The most notorious myth considers an eponymous Barbar as the ancestor of the Berbers. According to that myth, "the Berbers were the descendants of Ham, the son of Noah, the son of Barbar, the son of Tamalla, the son of Mazigh, the son of Canon" (Ibn Khaldun, The History of Ibn Khaldun, Chapter 3).
The fact that the name Berber is a strange name to the Berbers led to confusion. Some sources claim that the Berbers are several ethnic groups who are not related to each other. That is not accurate, because the Berbers refer to themselves as Imazighen throughout all of North Africa from Morocco to Libya including the Egyptian oasis of Siwa and about half of the Sahara Desert. In addition, genetic studies suggest a strong genetic bond between all the inhabitants of modern-day North Africa west of the Nile river.
The origins of both the names Berber and Amazigh is ambiguous. The oldest cited reference to "Amazigh" goes back to the neighboring ancient Egyptians when they mentioned an ancient Libyan tribe called Meshwesh. Those Meshwesh are supposed by some scholars to be the same ancient Libyan tribe that was mentioned as Maxyans by the Greek historian Herodotus.