acclivity vs inclination

acclivity

noun
  • A slope or inclination of the earth, as the side of a hill, considered as ascending, in opposition to declivity, or descending; an upward slope; ascent. 

inclination

noun
  • A slant or slope. 

  • A tendency. 

  • The angle of intersection of a reference plane 

  • A physical tilt or bend. 

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