kerf vs scarification

kerf

noun
  • The groove or slit created by cutting or sawing something; an incision. 

  • The portion or quantity (e.g. of wood, hay, turf, wool, etc.) removed or cut off in a given stroke. 

  • The distance between diverging saw teeth. 

  • The flattened, cut-off end of a branch or tree; a stump or sawn-off cross-section. 

verb
  • To cut a piece of wood or other material with several kerfs to allow it to be bent. 

scarification

noun
  • The scratching, etching, burning / branding, or superficially cutting designs, pictures, or words into the skin as a permanent body modification. 

  • A medieval form of penance in which the skin was damaged with a knife or hot iron. 

  • The act of scarifying: raking the ground harshly to remove weeds, etc. 

  • A route of administration for some vaccinations and tests: rather than hypodermic injection, the site is inoculated intradermally not with any injection but rather only with small, shallow pricks or scratches; the needle is not hollow. 

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