By comparing the texts of the book of Genesis, like the stories of the sons of God, the Deluge and the confusion of tongues (the Tower of Babel story), with the Mesopotamian myths, one should note these stories are not only very similar but also that there is the mention of multiple gods instead of one. The ancient Mesopotamian people knew, like the old Greeks, a whole pantheon of various dieties where each of one had his/her own place within the hierarchy. Like the Greek gods, the Mesopotamian dieties were not seen as the creators of the world but as the almighty rulers of a world which was already in existence. During the early time of the patriach Abraham many people still revered their previous rulers as gods.
The Mesopotamian gods existed of gods of the earth which were known as the "Anunnaki in Sumerian and the "Anunna" in Akkadian cultures, who were also called the "fifty great gods", and the gods of the sky or the heavens: the "Igigi", who were the so-called: "lesser gods". At times the names of Anunnaki and Igigi were used synonymously, what could mean that the Igigi were actually part of the Anunnaki. In the Babylonian myth of creation; the "Enuma Elish", the god Marduk (who triumped over his father Enlil) divided the Anunnaki and assigned them to their proper stations; three hundred in heaven and three hundred on the earth.
The local chief god Enlil (which could be translated to: "Lord of the Storm") was a stern but righteous god but when he was pushed to his limits he was merciless for anyone who opposed him. So when he saw the creation of modern man as a total failure he would have send out the great flood. (It is likely that the Hellenes knew Enlil as their chief god Zeus, because in Plato's dialogue Critias it would have been Zeus that brought out the great Deluge.)
His half brother Enki (translates to "Lord of the Earth" and known as "Ea" by the Akkadians") was an alchemist, advisor and a god of fertility and wisdom. He would have been involved with the creation of (modern) man, and therefore he was possibly also known in Greek mythology as the titan Prometheus, who created "mortal man". Enki was also the one who saved the pius man known as: Atrahasis (Akkadian), Utnapishtim (Sumerian) and Noah (by the later Babylonian and Hebrews), and his family from the flood.
Above Enlil and Enki stood the great Anu, the god of the heaven (firmament) and according to ancient Sumerian beliefs the supreme head of the gods. His kingdom was in the expansion of the heavens and is like the Greek god Ouranos (latinized: Uranus) - whose name is similar to the name Anu - known as a personification of the heavens/sky. According to the stories all other gods of the Anunnaki would be his descendants. His leadership was followed up by the god Enlil, what eventually lead to a conflict with his half brother Enki about who would be the righteous leader. Also the Sumerian goddess Inanna, granddaughter of Enlil and great-granddaugher of Anu, and known by the Akkadians as "Ishtar", has similarities with the Greek goddess Aphrodite, known by the Romans as Venus.
Print of a cylinder seal depicting several Sumerian gods.
The name "Anunnaki" is generally believed to mean something to the effect of "Those of Royal Blood" (Leick, Gwendolyn: "A Dictionary of Ancient Near Eastern Mythology"), but linguists are actually divided about its true meaning. The name is generally believed to be composed of the following words:
Anu, which is assumed to be the name of the Anunnaki’s supreme god. And the epistemological meaning of Anu is: Lord; leader; king. As a personification of the heaven/sky, his kingdom was "in the expanse of the heavens", just like the Greek god Ouranos/Uranus.
Na, is either a verb or an adverb, meaning "to send". In many Akkadian, Sumerian, Assyrian and Old Babylonian texts and inscriptions, “Na” was written as “Ina”, and meant in, from within, so on.
Ki, generally means "earth" in Akkadian and Sumerian, but also means "the underworld", "the netherworld", "the world of death". Maybe they regarded earth sometimes as the "world of death" because everything in the earthly "material word" eventually perishes.
Quite literary Anunnaki could both translate to: "Anu to earth' or "heaven to earth". In his book "The Twelfth Planet" (1976), author and expert in ancient languages Zecharia Sitchin translated this as: "(those who) from heaven to earth came".
The word Anunnaki is also somewhat similar to the name of the group of giants who are called "Anakim" in old Hebrew or Enkaites in the Biblical book Numbers, 13:32-33, which translates to "long-necked ones". The word "Anakim" is probably not a variantion of the word "Anunnaki" but would be one of the many names given to the giants or more a certain group of giants.