defacement vs graffito

defacement

noun
  • An act of defacing; an instance of visibly marring or disfiguring something. 

  • An act of voiding or devaluing; nullification of the face value. 

  • A symbol added to a flag or coat of arms to change it or make it different from another. 

graffito

noun
  • An informal inscription, as by a worker or vandal. 

  • A single instance of graffiti in the art/vandalism sense. 

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