What is an "Epic" Song?

Very few songs I would describe as "epic."  "Sweet Child O'Mine" perhaps, "Stairway to Heaven" certainly, "One" by Metallica probably.  I am not seeing a lot of "epic" songs these days.  I think I may have found one.    I have seen Dawes Live and they can pull it off better that way.  That being said, I am definitely a fan of the video and production on this one.  Do you think this qualifies as "epic"?  If not, what does better than this?