Speedometer vs. Tachometer

Speedometer and Tachometer Definitions
Speedometer
An instrument for indicating speed.
Tachometer
An instrument used to measure the rotations per minute of a rotating shaft.
Speedometer
An instrument for indicating distance traveled as well as rate of speed.
Tachometer
A device for measuring the revolutions per minute (RPMs) of a revolving shaft, as with the driveshaft of an automobile.
Speedometer
An odometer.
Tachometer
A device for measuring or indicating velocity or speed, as of blood, a river, a machine, etc.
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Speedometer
An instrument located within the dashboard of a vehicle that measures and indicates the current speed of the vehicle.
Tachometer
An instrument for measuring the velocity, or indicating changes in the velocity, of a moving body or substance.
Speedometer
Such a device incorporating an odometer.
Tachometer
An instrument for measuring the velocity of running water in a river or canal, consisting of a wheel with inclined vanes, which is turned by the current. The rotations of the wheel are recorded by clockwork.
Speedometer
A meter fixed to a vehicle that measures and displays its speed
Tachometer
An instrument for showing at any moment the speed of a revolving shaft, consisting of a delicate revolving conical pendulum which is driven by the shaft, and the action of which by change of speed moves a pointer which indicates the speed on a graduated dial.
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Tachometer
An instrument for measuring the velocity of the blood; a hæmatachometer.
Tachometer
Measuring instrument for indicating speed of rotation