Ademption by extinction refers to when an intended gift of property through a will fails to transfer those property rights because the property as described in the will no longer belongs to the testator when the will takes effect.
For example, if a mother were to devise a house to her son in her will, but sold the house before she died, the son cannot receive the house because the gift listed in the will was adeemed by extinction. Furthermore, the son is not entitled to the proceeds the mother obtained by selling the house because the property has changed its form such that it is no longer described in the will.
While obvious in some cases, whether a given change has sufficiently transformed property such that ademption occurred can sometimes be unclear. For example, some courts have held that exchanging one stock into another stock is insufficient to adeem. In unclear cases like these, courts tend to look at the intentions of the testator towards whether the changed property should still be given to the initial recipient.
[Last updated in June of 2022 by the Wex Definitions Team]