term:

Reversion

reversion n

[Anglo-French, from Middle French, from Latin reversio act of turning back, from revertere to turn back]
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
re·ver·sion·ary [-zhə-ner-ē]
adj