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n. An instrument used to measure the rotations per minute of a rotating shaft.

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

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

n. An instrument for measuring the velocity, or indicating changes in the velocity, of a moving body or substance.

n. 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.

n. 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.

n. An instrument for measuring the velocity of the blood; a hæmatachometer.

n. An instrument for measuring velocity.

n. measuring instrument for indicating speed of rotation

"To wit: The tachometer is the size of a wristwatch tucked into the left corner behind the steering wheel you can switch the display on the LCD screen, while the option for connecting to an iPhone takes prime and primary placement in the center console screen."

measuring device    measuring instrument    measuring system   

tachymeter   

tachograph   

haematachometer   

magneton    interpolator    speedometer    comparator    warp-field