@outlanderpod @JeSuisPrestNow @brianjaffa @heartsonycgr @Outlander_Starz So far, I've seen the books sold as: Literature, Fiction, Historical Fiction, History (nonfiction) (really), Science Fiction, Fantasy, Mystery, Romance, Military History, Gay and Lesbian Fiction, and...Horror. (True. I once beat George RR Martin _and_ Stephen King for a Quill Award in "Science-fiction/fantasy/horror"--and in the same year (and for the same book) won the Corine International Prize for Fiction.)
Now,the thing is--none of these designations are actually _wrong_, but you do want to be careful how you describe the books to someone. Calling them romances, for instance, will discourage most male readers, whilst calling them science fiction (as indeed they are; I was asked to write up The Gabaldon Theory of Time-Travel for the Journal of Transfigural Mathematics (Berlin)--and did)is likely to give people visions of Tardises, Morlocks, and the sorts of logistical problems that result from accidentally giving birth to yourself. All fascinating elements, of course, but really not resembling the sort of thing that happens in my novels.
As my beloved first editor used to say, "These _have_ to be word-of-mouth books, because they're too weird to describe to anybody." This is absolutely true. Fortunately, we're about to be able to say, "They've made a great tv show of it," and that will work very nicely, too.