dynasty vs incumbency

dynasty

noun
  • The polity or historical era under the rule of a certain dynasty. 

  • A series of rulers or dynasts from one family. 

  • A team or organization which has an extended period of success or dominant performance. 

incumbency

noun
  • The state of being incumbent. 

  • Benefice, lucrative position or possession. 

  • A tenure. 

  • An obligation or duty. 

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