prong vs quoin

prong

verb
  • To pierce or poke with, or as if with, a prong. 

noun
  • A thin, pointed, projecting part, as of an antler or a fork or similar tool. A tine. 

  • The penis. 

  • A branch; a fork. 

quoin

verb
  • To wedge or steady with quoins. 

noun
  • Any of the corner building blocks of a building, usually larger or more ornate than the surrounding blocks. 

  • The keystone of an arch. 

  • A number of apple varieties with a distinctive ribbed appearance, like corners of a coin. 

  • A metal wedge which fits into the space between the type and the edge of a chase, and is tightened to fix the metal type in place. 

  • A wedge of wood or iron put under the breech of heavy guns or the muzzle of siege-mortars to raise them to the proper level. 

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