egress vs ingression

egress

noun
  • The process of exiting or leaving. 

  • The end of the transit of a celestial body through the disk of an apparently larger one. 

  • An exit or way out. 

verb
  • To exit or leave; to go or come out. 

ingression

noun
  • The act or process of entering or intruding. 

  • The process by which a potentiality enters into actuality. 

  • The inward migration of cells from the blastula during gastrulation. 

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