An instrument used to measure distance traveled.
Example:
Jennifer watched the odometer to see how far she would have to drive to her new job.
Odometer includes the root from the Greek word hodos, meaning "road" or "trip." The odometer is what unscrupulous car salesmen illegally tamper with when they want to reduce the mileage a car registers as having traveled. One of life's little pleasures is watching the odometer when all of the numbers change at the same time.