breakage

Short definition from Wiktionary

Noun

1. 1
   The act of breaking.
2. 2
   Something that has been broken.
3. 3
   A service which is unused by a customer, such as an unredeemed gift card, which therefore represents a pure profit to the seller.
4. 4
   The left-over money in a pari-mutuel betting pool resulting from rounding off the payoffs, added to the pool for the next race or event or kept as profit.