Reversion

Reversion, the estate which reverts or returns to a grantor after the grant of a particular estate or interest in the property. This reversion is founded on the principle that where a person has not parted with his whole estate or interest in the land, all that which he has not parted with remains in him, and the possession of the land reverts or returns to him upon the determination of the preceding estate - i.e. the estate which remains after the grant. In other words, it is "the residue of the estate left in the grantor."