tachometer vs timer

tachometer

noun
  • A device for measuring or indicating velocity or speed, as of blood, a river, a machine, etc. 

  • A device for measuring the revolutions per minute (RPMs) of a revolving shaft, as with the driveshaft of an automobile. 

timer

noun
  • A device used to measure amounts of time. 

  • Any electronic function that causes a device to be able to do something automatically after a preset amount of time. 

  • A person who records the time elapsed in a sporting event. 

  • One who has done something a certain number of times. 

  • One characterized by a certain time or time frame, such as their work hours. 

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