The term is most often used to describe completely fabricated stories. Fake news is not to be confused with satirical news as seen on shows like "Saturday Night Live" or in publications like “The Onion." Fake news is not a humorous comment on the news. Rather, fake news seeks to supplant the news, to sway its audience into believing all sorts of untruths and conspiracy theories, the more bizarre, the better."
http://www.ifla.org/publications/node/11174