constancy vs notion

constancy

noun
  • The quality of being constant; steadiness or faithfulness in action, affections, purpose, etc. 

  • An unchanging quality or characteristic of a person or thing. 

notion

noun
  • Inclination; intention; disposition. 

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

  • A sentiment; an opinion. 

  • An invention; an ingenious device; a knickknack. 

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

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