carry-on vs mailboat

carry-on

noun

  • That luggage or baggage which is taken onto an airplane (or a ferry, etc.) with a passenger, rather than checked. 

  • A bag, suitcase, etc., used to carry this luggage or baggage. 

  • A palaver; a disorderly or absurd situation. 

adj

  • Taken onto an airplane (or a ferry, etc.) with a passenger, rather than checked. 

mailboat

noun

  • A boat used to transport mail. 

How often have the words carry-on and mailboat occurred in a corpus of books? (source: Google Ngram Viewer )