senescent vs senile

senescent

adj
  • Characteristic of old age. 

  • That ceases to divide. 

  • Growing old; decaying with the lapse of time. 

senile

adj
  • Of, or relating to old age. 

  • Exhibiting the deterioration in mind and body often accompanying old age; doddering. 

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