acclivity vs incline

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. 

incline

noun
  • A slope. 

  • A portal of a subway tunnel. 

verb
  • To bend or move (something) out of a given plane or direction, often the horizontal or vertical. 

  • To tend to do or believe something, or move or be moved in a certain direction, away from a point of view, attitude, etc. 

  • To slope. 

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