The word Abraxas (or Abrasax or Abracax) was engraved on certain antique stones, called on that account Abraxas stones, which were used as amulets or charms. The name is found in the Greek Magical Papyri, and the word may be related to the word abracadabra, although other explanations exist. The name is also found in Gnostic texts such as the Gospel of the Egyptians. Abraxas has also been variously claimed throughout the centuries to be an Egyptian god, a demon, and to represent God and Satan in one entity and the dual nature of its essence.The initial spelling of the word as seen on stones was "Abrasax" (???????). The spelling seen today probably originates in the confusion made between the Greek letters Sigma and Xi in the Latin transliteration.
Appearance and meaning
The letters of Abraxas (???????), in the Greek system of alphabetic numerology, sum to the number 365, and the Basilideans gave the name to the 365 orders of spirits which, as they conceived, emanated in succession
Source:
http://en.wikipedia.org/wiki/Abraxas