commissioner vs plenipotentiary

commissioner

noun
  • An official in charge of a government department, especially a police force. 

  • Someone commissioned to perform certain duties. 

  • A member of a commission. 

  • Someone who commissions something. 

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 commissioner and plenipotentiary occurred in a corpus of books? (source: Google Ngram Viewer )