duffel bag vs overnighter

duffel bag

noun
  • A large, cylindrical, duffel cloth bag used to carry personal gear, especially by soldiers. 

  • A smaller, cylindrical, cloth bag fashionable in the 1950s and 1960s. 

overnighter

noun
  • Something that serves overnight travel, such as a night train. 

  • A person who overnights, or stays overnight. 

  • A stay or event that takes place overnight. 

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