what hipsters, idiots, and the media use to attempt to sound high brow about reading/discussing comic books, but in reality is a term describing a specific format of comic book. that form being an over-sized self-contained single original story (as opposed to a typical single issue or collection of old single issues).
proper: hey, did you read the new Will Eisner graphic novel? you know the one that actually says graphic novel on it and everything?
improper: X-Men is my favorite graphic novel!