I hate the word epic and its overuse today. It means nothing to me anymore.
I agree, people should simply learn what words mean before using them.
Epic is a measure of quantity, not quality. More specifically the length of a story.
If you write a book it's considered epic if it's length is over 100.000 words.
Skyrim won't have 100.000 words of dialog, but if you count all the landscapes, buildings and other content I guess it would easily be worthy to be called epic.