infiltration vs intrusion

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. 

intrusion

noun
  • The forcible inclusion or entry of an external group or individual; the act of intruding. 

  • The insertion of a phoneme into the pronunciation of a word despite its absence from the spelling. (e.g. intrusive r) 

  • A structure that lies within a historic district but is nonhistoric and irrelevant to the district. 

  • Magma forced into other rock formations; the rock formed when such magma solidifies. 

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