mezzotint vs scarification

mezzotint

noun
  • An etching or print made using this method. 

  • A form of intaglio etching in which a metal plate is roughened evenly and then smoothed to bring out an image. 

verb
  • To make such etchings 

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 mezzotint and scarification occurred in a corpus of books? (source: Google Ngram Viewer )