grizzled vs senile

grizzled

adj
  • greyed, old 

  • streaked or mixed with grey; grizzly; griseous 

  • grey or partly grey 

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 grizzled and senile occurred in a corpus of books? (source: Google Ngram Viewer )