centenary vs centennium

centenary

noun
  • Synonym of centennial: a hundredth anniversary. 

  • Synonym of hundredman: a position in the Anglo-Saxon kingdoms overseeing local administration. 

  • Synonym of centgrave: a position in the Frankish Empire overseeing local administration. 

  • Synonym of hundredweight, especially (historical) in Greek and Roman contexts. 

adj
  • Occurring every 100 years. 

  • Lasting or aged 100 years, 100-year-old. 

centennium

noun
  • Synonym of century: A period of 100 years. 

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