graffiti vs moisten

graffiti

verb
  • To mark a surface with such images. 

noun
  • Drawings or words drawn on a surface in a public place, usually made without authorization. 

  • Informal inscriptions, figure drawings, etc., as opposed to official inscriptions. 

moisten

verb
  • To make moist or moister. 

  • To become moist or moister. 

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