incursion vs infiltration

incursion

noun
  • An aggressive movement into somewhere; an invasion. 

infiltration

noun
  • The act of secretly entering a physical location and/or organization. 

  • The substance which has entered the pores or cavities of a body. 

  • process by which water on the ground surface enters the soil. 

  • The act or process of infiltrating, as of water into a porous substance, or of a fluid into the cells of an organ or part of the body. 

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