Why is the Odyssey characterized as an epic?

An odyssey is a long and adventurous journey such as the return of Odysseus from the Trojan War, often with the additional idea of a search for an intellectual or spiritual goal. The most famous odyssey story of modern times is Ulysses (the Latin name for Odysseus) by James Joyce in which Leopold Bloom (Ulysses) wanders through the streets of Dublin for a whole day having a series of meetings and adventures before returning home to his wife Molly.