Breakage is a term used in accounting to indicate gift cards that have been sold but never redeemed. Revenue from breakage is almost entirely profit, since companies need not provide any goods or services for unredeemed gift cards.
Breakage is a term used in sales, distribution, and multi-level marketing organizations to indicate commissions that are lost for the failure to meet certain conditions or requirements. Revenue from breakage is almost entirely profit as commissions lost for failure to meet those conditions or requirements can never be recovered.
Breakage is also used in the Telecommunications industry to refer to a scenario where the customer does not receive the full value of a service due to some specific charging mechanism or limitation. It is an important component of the profit in many Telecommunications services.
Breakage on Wikipedia.