Source : Webster's Revised Unabridged Dictionary (1913)

Odyssey \Od"ys*sey\, n. [L. Odyssea, Gr. ?, fr. ? Ulysses: cf.F.
   Odyss['e]e.]
   An epic poem attributed to Homer, which describes the return
   of Ulysses to Ithaca after the siege of Troy.

Source : WordNet®

odyssey
     n 1: a long wandering and eventful journey
     2: a Greek epic poem (attributed to Homer) describing the
        journey of Odysseus after the fall of Troy