alarm clock vs speedometer

alarm clock

noun
  • A clock with an alarm that can be set to sound at a determined time. 

speedometer

noun
  • Such a device incorporating an odometer. 

  • An instrument located within the dashboard of a vehicle that measures and indicates the current speed of the vehicle. 

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