If something is uncanny, it is so mysterious, strange, or unfamiliar that it seems supernatural. If you hear strange music echoing through your attic, you might refer to it as positively uncanny.
You can also use uncanny to refer to something that is so remarkable that it is beyond what is natural, as in "She has an uncanny ability to find her way around new places." This adjective was formed in English from the prefix un-, "not," and canny, "fortunate, safe." The current meaning of English canny is "careful and clever, especially in handling money."