début vs ingression

début

noun
  • A person’s or thing’s first appearance before society or another audience; one’s “maiden voyage”. 

verb
  • To make one's début. 

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 début and ingression occurred in a corpus of books? (source: Google Ngram Viewer )