ectype vs similarity

ectype

noun
  • An idea or impression that corresponds to external reality. 

  • A copy, reproduction; especially as contrasted with the original, archetype, or prototype. 

  • An object in relievo or embossed. 

  • An impression (in wax, clay, &c.) of a seal or medal. 

similarity

noun
  • Closeness of appearance to something else. 

  • A transformation that preserves angles and the ratios of distances 

  • The property of two matrices being similar. 

  • The relation of sharing properties. 

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