genarian vs oldster

genarian

noun
  • An elderly person, especially one over the age of 60. 

adj
  • Concerning rules or principles as opposed to acts. 

oldster

noun
  • Someone who is old. 

  • A midshipman of four years' standing; a master's mate. 

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