Epic (n.)(a.) - How definitions change and who should change them.
Impressive, heroic or remarkable.
Also related to or with similar themes and traits as an epic poem.
A genre of poetry, generally long with rhyming or alliterative verse.
History & Etymology
Ok, well it’s not that epic and it’s actually pretty recently when this definition change took place. 1983 is when the first time epic was recorded as being used to describe impressive or remarkable.
USA Today 29 Sept. 1983 When University of Florida linguistics professor David Pharies asked 350 sophomores for samples of college slang, here's what he found... ‘Killer’ is a compliment, along with ‘mint, awesome, prime, epic, golden, [etc.]’.
I was born in 1983 and this usage of the word was the one I grew up with. I even assumed that the poems were called epics because they were long and about heros and remarkable events. Prior to this definition the word epic was primarily applied to the poetry or other forms of art that took inspiration from the art form.
Over time people, mainly children, heard the word used in association with books, music and movies, but they may not have known about the poetry. Like me they may have assumed the word meant remarkable.
But really the word originally referred to the voice, the medium that epic poetry was created in. The PIE root was wekw- the same original root as voice.