cavalry vs straphanger

cavalry

noun
  • An individual unit of the cavalry arm of service. 

  • Source of rescue, especially in an emergency. 

  • The branch of the military transported by fast light vehicles, also known as mechanized cavalry. 

  • The military arm of service that fights while riding horses. 

straphanger

noun
  • A person who travels using public transportation (often standing up and holding on to a strap). 

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