revertible
  (a.)可回復的,應歸還的
  re·vert·ible /-ˈvɝtəbəl/ 形容詞
  Re·vert·i·ble a. Capable of, or admitting of, reverting or being reverted; as, a revertible estate.
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  revertible
       adj : to be returned to the former owner or that owner's heirs