A more thorough explanation:

Definition: A person who is appointed as an heir in the decedent's will.

Example: John's grandfather passed away and left a will that appointed John as the testamentary heir. This means that John is entitled to receive the property that his grandfather left behind according to the terms of the will.

Explanation: A testamentary heir is someone who is named as an heir in a will. This is different from an heir who receives property through the laws of intestacy, which apply when someone dies without a will. In the example, John is appointed as the testamentary heir in his grandfather's will, which means that he will receive the property that his grandfather left behind according to the terms of the will.