Emily Dickinson Lexicon

A-O'NI-AN, a. [From Aonia, a part of Bœotia, in Greece.]

Pertaining to the muses, or to Aonia, in Bœotia. The Aonian fount was Aganippe, at the foot of Mount Helicon, not far from Thebes, and sacred to the muses. Hence the muses were called Aonides. Dryden's Virgil, Eclogue 10. 12. But in truth, Aonia itself is formed from the Celtic aon, a spring or fountain, [the fabled son of Neptune,] and this word gave name to Aonia. As the muses were fond of springs, the word was applied to the muses, and to mountains which were their favorite residence, as to Parnassus. Milton.