reversion

noun | \ ri-ˈvər-zhən \ | re·ver·sion

1. : the returning of an estate upon its termination to the former owner or to his or her successor in interest

2. a : the present vested interest in the residue of an estate that remains in its owner after the grant therefrom of a lesser estate (as a life estate) and that will commence in possession by operation of law upon termination of the lesser estate

   b : the future interest in property left in a grantor or his or her successor in interest that is not subject to a condition precedent — compare possibility of reverter, remainder