speedometer -
A device that measures, and indicates the current speed of a vehicle.
speedometer -
Such a device incorporating an odometer.
Wikipedia
A speedometer is a device that measures the instantaneous speed of a land vehicle. Now universally fitted to motor vehicles, they started to be available as options in the 1900s, and as standard equipment from about 1910 onwards. Speedometers for other vehicles have specific names and use other means of sensing speed.