Definitions:

1. A device that automatically records a vehicle's speed, distance traveled, and driving/rest times, primarily used in commercial transport to monitor driver activity and ensure legal compliance. NOUN
   • The inspector checked the truck's tachograph to verity that the driver had not exceeded the legal driving limit.
2. A device that records the distance and time traveled by a vehicle, used to check the driver's working time. NOUN
   • The tachograph mandates that drivers take regular breaks and adhere to maximum driving time limits.