What is Expectancy?

Legal Definition
Estates. Having a relation to or dependence upon something future.

2. Estates are of two sorts, either in possession, sometimes called estates executed; or in expectancy, which are executory. Expectancies are, first, created by the parties, called a remainder; or by act of law, called a reversion.

3. A bargain in relation to an expectancy is, in general, considered invalid. 2 Ves. 157; Sel. Cas. in Ch. 8; 1 Bro. C. C. 10; Jer. Eq. Jur. 397.
-- Bouviers Law Dictionary
Legal Definition
The condition of being deferred to a future time, or of dependence upon an expected event; contingency as to possession or enjoyment. With respect to the time of their enjoyment, estates may either be in possession or in expectancy ; and of expectancies there are two sorts--one created by the act of the parties, called a "remainder;" the other by act of law, called a "reversion." 2 Bl. Comm. 163.
-- Black's Law Dictionary
Legal Definition
A present estate, the use and enjoyment of which are future. See 56 Am. St. Rep. 339, note.
-- Ballentine's Law Dictionary