notion vs speculative fiction

notion

noun
  • An invention; an ingenious device; a knickknack. 

  • Mental apprehension of whatever may be known, thought, or imagined; idea, concept. 

  • A sentiment; an opinion. 

  • Any small article used in sewing and haberdashery, either for attachment to garments or as a tool, such as a button, zipper, or thimble. 

  • Inclination; intention; disposition. 

speculative fiction

noun
  • A particular work belonging to this class. 

  • A class of fiction involving fantastic, supernatural or futuristic elements, including fantasy, horror, and science fiction, dealing with worlds, themes, and characters not part of everyday life. 

How often have the words notion and speculative fiction occurred in a corpus of books? (source: Google Ngram Viewer )