alderman vs commissioner

alderman

noun
  • A member of a municipal legislative body in a city or town. 

  • A long pipe for smoking. 

  • A potbelly, paunch. 

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. 

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