eldern vs senile

eldern

adj
  • Elder; elderly; aged; old. 

  • Not new; old; ancient. 

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