acclivity vs summit

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. 

summit

noun
  • A peak; the topmost point or surface, as of a mountain. 

  • A gathering or assembly of leaders. 

verb
  • To reach the summit of a mountain. 

pron
  • Something 

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