bygone vs centenarian

bygone

adj
  • Having been or happened in the distant past. 

noun
  • An event that happened in the past. 

centenarian

adj
  • Of or relating to centenarians or a centenary celebration. 

  • Aged 100 years or more; extremely old. 

noun
  • One who or that which is at least 100 years old. 

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