illegal alien vs stranger

illegal alien

noun
  • A person who is within the boundaries of a political state without the authorization of the government of that state; a national of another country who has entered or stayed without permission. 

stranger

noun
  • One not privy or party to an act, contract, or title; a mere intruder or intermeddler; one who interferes without right. 

  • One who has not been seen for a long time. 

  • A person whom one does not know; a person who is neither a friend nor an acquaintance. 

  • A newcomer. 

  • An outsider or foreigner. 

  • One not admitted to communion or fellowship. 

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