grey-haired vs senescent

grey-haired

adj
  • old, wise, experienced. 

  • Having grey hair. 

senescent

adj
  • Characteristic of old age. 

  • That ceases to divide. 

  • Growing old; decaying with the lapse of time. 

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