executory interest

Noun

 * 1)  A third-party interest in an estate in land created by the conditions of a grant wherein the grantor gives the land to a second party, but with said land going to a third party upon the occurrence of a condition; an interest created subject to a fee simple subject to executory interest.
 * Joe gives land "to Mike, but if Harry graduates from law school, to Harry". Harry has an executory interest which he can realize by graduating from law school; Mike owns the land subject to Harry's executory interest.