n.1. Total length, extent, or distance measured or expressed in miles.
2. Total miles covered or traveled in a given time.
3. The amount of service, use, or wear estimated by miles used or traveled: This tire will give very good mileage.
4. The number of miles traveled by a motor vehicle on a given quantity of fuel.
5. a. An allowance for travel expenses established at a specified rate per mile.
b. Expense per mile, as for the use of a car.
6. Informal The amount of service something has yielded or may yield in the future; usefulness: a tape player that still has a lot of mileage left.