Septuagint is the word for the first Greek translation of the Hebrew Bible. It became the basis for Bible translations into many other languages, including Ethiopian, Arabic and Armenian.
The name Septuagint, which means 70 in Latin, comes from the story of the books creation. The Talmud, in tractate Megillah (9a-9b), recounts how Ptolemy, a third-century-BCE Egyptian Pharaoh, gathered together 72 Jewish sages (close to 70), put them in 72 separate house and demanded that each produce independently a Greek translation of the Hebrew Bible.
Miraculously, they all came out with the same version. Even more remarkably, they had all decided in 15 places to give an unusual, non-literal translation.
These 15 points are listed by the Talmud. Most are places where a literal rendering might have given rise to theological misunderstandings. However, in one of them, (Leviticus 11:6), the Talmud says that the sages translated arnevet as short-legged animal, rather than rabbit, because Ptolemys wifes name was Rabbit,and the translators wanted to avoid any suspicion that they were making fun of her.
The Greek Letter of Aristeas retells this story and embellishes it with some extra details, including that six of the sages came from each tribe and that they completed their work in exactly 72 days. According to Wikipedia, many scholars think that the Letter of Aristeas, which purports to be a contemporary account, was written later.