Vest

Verb. To accrue to; to be fixed; to give a fixed and indefeasible right; to grant. To come or descend to; to be fixed; to take effect, as a title or right. Upon the death of the ancestor, the estate, or the right to the estate, vests in the heir at law.

A right or an interest in property "vests" when it is secured. This means that the beneficiary of the right or property interest is certain to receive a specific amount, either now or in the future.