In this article, I have investigated firstly the beginning of the Persian and Arabic philosophy in later antiquity and then adoption of greek philosophical definitions in the Eastern world In the arabic world as well as in the western Scholasticism, the Aristotelian sciences was dominant after 10th century, but in the earlier times(6-9th centuries), the thoughts of Neoplatonists as Plotinus, Porphyry and Proclus exercised influences very strongly and their works were more widespread and had been investigated. It depended upon the academic roles of seven Neoplatonic philosophers as Damascus and Simplicius who had moved from the christianized Rome to East, the Empire of Persia, after closing of the Athenian Academia in 527 A.D. Under the protection of the Sassanid Emperor Khosrau I, they worked in translating greek philosophical texts into Persian Pahlavi and taught greek philosophical thoughts at Academy of Gondischapur, the renowned Persian academdic center of learning in later antiquity. Even after the greek philosophers left Persian empire, persian and arabic philosophers developed the greek philosophy through translating and commentating works of greek texts and further used the greek philosophical thought to the developing and interpreting works of islam doctrines, mostly in positive way, but sometimes critically. However, as their main tasks adopted the arabic philosophers in that times six definitions of philosophy arranged by Alexandrian Neoplatonists, as introduced well in David's prolegomena philosophiae, and rearranged and reinterpreted them from their own theological viewpoint. With this work, decided the arabic philosophers orientation of philosophical studies and education in arabic world, and developed their philosophy and theology fundamentally.