aging vs centenarian

aging

adj
  • Becoming elderly. 

noun
  • The process of becoming older or more mature. 

  • The accumulation of damage to macromolecules, cells, tissues and organs with the passage of time; the progressing loss of health, mobility, vibrancy and body functionality, resulting in biological death. 

  • The deliberate process of making something (such as an antique) appear (or, in science fiction, become) older than it is. 

  • Wear; wear and tear. 

centenarian

adj
  • Aged 100 years or more; extremely old. 

  • Of or relating to centenarians or a centenary celebration. 

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

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