nuncio vs plenipotentiary

nuncio

noun
  • The ecclesiastic title of a permanent diplomatic representative of the Roman Catholic Church to a sovereign state or international organization, who is accorded a rank equivalent to an accredited ambassador, and may also be given additional privileges including recognition as Dean in a country's diplomatic corps. 

  • Any member of any Sejm of the Kingdom of Poland, Polish–Lithuanian Commonwealth, Galicia (of the Austrian Partition), Duchy of Warsaw, Congress Poland, or Grand Duchy of Posen. 

  • One who bears a message; a messenger. 

plenipotentiary

noun
  • A person invested with full powers, especially as the diplomatic agent of a sovereign state, (originally) charged with handling a certain matter. 

adj
  • Of or relating to a plenipotentiary agent 

  • Invested with full power. 

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