If something is so new and original that it's never been seen, used or even thought of before, call it novel. The noun novel describes a book-length work of fiction.
New and novel come from the same Indo-European root but by different paths. Whereas new is a Germanic word coming from Old English, novel is based on Latin novellus "new, young, fresh." If something is novel, it is new but also original, fresh and unique. Companies are always looking for that novel idea that will earn them millions and skydiving is a novel experience, especially if you're not adventurous.