senescent vs septuagenarian

senescent

adj
  • Characteristic of old age. 

  • That ceases to divide. 

  • Growing old; decaying with the lapse of time. 

septuagenarian

adj
  • Of or related to seventysomethings. 

noun
  • Synonym of seventysomething: a person between 70 and 79 years old. 

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