not long for this world vs senescent

not long for this world

adj
  • Unlikely to endure for much more time. 

senescent

adj
  • Growing old; decaying with the lapse of time. 

  • Characteristic of old age. 

  • That ceases to divide. 

How often have the words not long for this world and senescent occurred in a corpus of books? (source: Google Ngram Viewer )