dispatcher vs teamster

dispatcher

noun
  • In a transportation organization, a person who controls the movements of vehicles. 

  • Any die used for cheating, whether fraudulently weighted or bearing duplicate numbers. 

  • A piece of software responsible for assigning priorities and resources to tasks waiting to be scheduled. 

teamster

noun
  • A person who drives a cargo truck (see Teamster). 

  • A person who drives a team of animals (such as horses or oxen). 

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