An
odometer or
odograph is an instrument that indicates
distance traveled by a vehicle, such as a bicycle or automobile. The device may be electronic, mechanical, or a combination of the two. The word derives from the
Greek words
hodós ("path" or "gateway") and
métron ("measure"). In countries where
Imperial units or
US customary units are used, it is sometimes called a
mileometer or
milometer, the former name especially being prevalent in the
United Kingdom and members of the
Commonwealth.