An adjective used for describing something that is both epic and cool; you know, like a copy of the Iliad in a refrigerator, our known universe and its temperature, juggling fifteen knives, or a death-defying parkour move.
(1) I can't believe I forgot my copy of the Iliad in the freezer! That's epiccool, literally.
(2) The Hubble 3D IMAX is tot's epiccool.
(3) Kids, I'm about to juggle fifteen knives. Don't try this at home unless you're epiccool.
(4) Did you see that guy who did a triple backflip after running up that wall? Epiccool.