For anyone who does not know, a graphic novel is a serious literary work in comic book form, like Art Spiegelman's ''Maus'' or Jules Feiffer's ''Tantrum.'' If comics are ''those bright, colorful magazines filled with bad art, stupid stories and guys in tights,'' as Scott McCloud jokingly put it in his book ''Understanding Comics'' (Kitchen Sink Press, 1993), then graphic novels are their earnest offspring. The tights are gone, the stories are often grim, and the drawing . . . well, it isn't exactly comic.