acclivity vs barrow

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. 

barrow

noun
  • A hill. 

  • A castrated boar. 

  • A long sleeveless flannel garment for infants. 

  • A mound of earth and stones raised over a grave or graves. 

  • A small vehicle used to carry a load and pulled or pushed by hand. 

  • A wicker case in which salt is put to drain. 

  • A heap of rubbish, attle, or other such refuse. 

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