The Collaborative International Dictionary of English v.0.48:

Aonian \A*o"ni*an\ ([asl]*[=o]"n[i^]*an), a. [From Aonia, a part
   of B[oe]otia, in Greece.]
   Pertaining to Aonia, in B[oe]otia, or to the Muses, who were
   supposed to dwell there.
   [1913 Webster]

   Aonian fount, the fountain of Aganippe, at the foot of
      Mount Helicon, not far from Thebes, and sacred to the
      Muses.
      [1913 Webster]