etching vs imprinting

etching

noun
  • The art of producing an image from a metal plate into which an image or text has been etched with acid. 

  • The image created by this process. 

imprinting

noun
  • Any kind of phase-sensitive learning (learning occurring at a particular age or a particular life stage) that is rapid and apparently independent of the consequences of behavior. 

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