pensionary vs senior citizen

pensionary

noun
  • one who receives a pension; a pensioner 

  • A leading functionary and legal adviser of the principal town corporations in the Netherlands. 

adj
  • pertaining to a pension 

  • maintained by a pension; receiving a pension 

senior citizen

noun
  • An old person, variously considered to be a person over fifty, fifty-five, sixty, or sixty-five years of age. 

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