The Collaborative International Dictionary of English v.0.48:

Hellenist \Hel"len*ist\, n. [Gr. ?: cf. F. Hell['e]niste.]
   1. One who affiliates with Greeks, or imitates Greek manners;
      esp., a person of Jewish extraction who used the Greek
      language as his mother tongue, as did the Jews of Asia
      Minor, Greece, Syria, and Egypt; distinguished from the
      Hebraists, or native Jews (--Acts vi. 1).
      [1913 Webster]

   2. One skilled in the Greek language and literature; as, the
      critical Hellenist. Hellenistic