After reading all these replies it seems like the word epic has yet another meaning: OPINION.

I have to throw another term into the fray:

saga

Star Wars, Indiana Jones, Godfather to me are all sagas and not epics. Lord of the Rings is a saga made up of three epic films.

My definition of epic: grand scale cinematically...lots of extras, lots of characters, grandiose locations and effects, usually overly long, and at times, melodramatic.

Examples: Braveheart, Dances with Wolves, Lawrence of Arabia