bulge vs knap

bulge

noun
  • Something sticking out from a surface; a swelling, protuberant part; a bending outward, especially when caused by pressure. 

  • The outline of male genitals visible through clothing. 

  • A sudden rise in value or quantity. 

  • The bilge of a vessel. 

  • The bilge or protuberant part of a cask. 

verb
  • To bilge, as a ship; to founder. 

  • To stick out from (a surface). 

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. 

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