Speedometer (noun)

An instrument in a vehicle, typically a car, that measures and displays the speed at which the vehicle is traveling.

Origin:

Early 20th century: from speed + -ometer.

Examples:

1. He checked the speedometer to make sure he wasn't exceeding the speed limit.
2. The speedometer showed that the car was traveling at 60 mph.
3. The speedometer was an essential instrument for the driver.
4. The speedometer was mounted on the dashboard.
5. The speedometer was a standard feature in most vehicles.