Financial reward for an employee which does not pay out until a certain amount of time has elapsed, so that there is an incentive for sticking around with the company. Examples include deferred compensation (like a year end bonus), company payments for leases or tuition (immediate reward but a substantial financial penalty if you leave the company), and with stock options, a vesting schedule (An outright stock grant lets the employee walk away richer... waiting for options to vest means the employee is voluntarily "handcuffed" to the employer).