Here’s an excerpt from Frederic Copleston’s A History of Philosophy: Augustine to Scotus (Volume II) (Page 561):
“In a sense we can say that neo-Platonism, Augustinianism, Aristotelianism and the Moslem and Jewish philosophies came together and were fused in Thomism, not in the sense that selected elements were juxtaposed mechanically, but in the sense that a true fusion and synthesis was achieved under the regulating guidance of certain basic ideas. Thomism, in the fullest sense, is thus a synthesis of Christian theology and Greek philosophy (Aristotelianism, united with other elements, or Aristotelianism, interpreted in the light of later philosophy) in which philosophy is regarded in the light of theology and theology itself is expressed, to a conservable extent, in categories borrowed from Greek philosophy, particularly from Aristotle.”
... Thomism is a synthesis of Christian theology and Greek philosophy, which might seem to imply that Thomism in the narrower sense, that is, as denoting simply the Thomist philosophy, is a synthesis of Greek philosophy and that it is nothing else but Greek philosophy. In the first place, it seems preferable to speak of Greek philosophy rather than of Aristotelianism, for the simple reason that St. Thomas’s philosophy was a synthesis of Platonism (using the term in a wide sense, to include neo-Platonism) and of Aristotelianism, though one should not forget that the Moslem and Jewish philosophers were also important influences in the formation of his thought.