rebate

rebate (http://definr.com/rebate)

     n 1: a refund of some fraction of the amount paid [syn: discount]
     2: a rectangular groove made to hold two pieces together [syn:
        rabbet]
     v 1: give a rebate
     2: as of timber or stone [syn: cut a rebate in]
     3: join with a rebate, as of pieces of timber or stone