knap vs prominence

knap

noun
  • A protuberance; a swelling; a knob. 

  • A small hill 

  • A sharp blow or slap. 

  • The crest of a hill 

verb
  • To rap or strike sharply. 

  • To shape a brittle material having conchoidal fracture, usually a mineral (flint, obsidian, chert etc.), by breaking away flakes, often forming a sharp edge or point. 

  • To make a sound of snapping. 

prominence

noun
  • A bulge: something that bulges out or is protuberant or projects from a form. 

  • The state of being prominent: widely known or eminent. 

  • Autonomous height; relative height or prime factor; a concept used in the categorization of hills and mountains. 

  • A gaseous projection, often loop-shaped, springing from the surface of the Sun or a star. 

  • Relative importance. 

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