A more thorough explanation:

Expectancy refers to the potential share of an estate that an heir may inherit upon the death of an ancestor. However, since expectancies are not yet vested, their transfer is generally considered void under common law.

For example, if a person's grandfather has a will that leaves a portion of his estate to his grandchildren, those grandchildren have an expectancy in the estate. However, until the grandfather passes away and the will is executed, the grandchildren do not have a guaranteed right to the inheritance.

It is possible for an expectancy to be released or given up in exchange for something of value, such as money or property. This can be recognized by courts as long as it is done without fraud or coercion.

Expectancy can also refer to the expectation of a business relationship that has been wrongfully interfered with. For instance, if a company intentionally causes a business partner to break a contract with another company, the affected company may have an expectancy claim against the interfering company.