courier vs explanator

courier

noun
  • A person who delivers messages. 

  • A company that transports goods. 

  • A user who earns access to a topsite by uploading warez. 

  • A company that delivers messages. 

  • A person who looks after and guides tourists. 

verb
  • To deliver by courier. 

explanator

noun
  • One who explains. 

  • A variable that predicts or explains the variation in another variable; an explanatory variable. 

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