airmail vs transmit

airmail

verb
  • To send mail by air. 

  • To (unintentionally) throw the ball well over a fielder's head where that fielder is unable to make a play on the ball. 

noun
  • The items of mail so carried. 

  • The system of conveying mail using aircraft. 

transmit

verb
  • To send or convey something from one person, place or thing to another. 

  • To spread or pass on something such as a disease or a signal. 

  • To communicate news or information. 

  • To convey energy or force through a mechanism or medium. 

  • To impart, convey or hand down something by inheritance or heredity. 

  • To send out a signal (as opposed to receive). 

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