REBATE

noun

1. A deduction from an amount that is paid; an abatement.
2. The return of part of an amount already paid.
3. The edge of a roll of film, from which no image can be developed.

verb

1. To deduct or return an amount from a bill or payment
2. To diminish or lessen something
3. To beat to obtuseness; to deprive of keenness; to blunt; to turn back the point of, as a lance used for exercise.