A more thorough explanation:

Mort d'ancestor

Mort d'ancestor means "death of an ancestor" in Law French. It was a type of legal case in the past that was based on the death of an ancestor. The case was used to determine if the plaintiff's father or other close ancestor had an inheritable estate when they died and if the plaintiff was their next heir. If both questions were answered yes, the plaintiff was entitled to inherit the estate.

An example of a case that could be considered a mort d'ancestor case is if a person's father died and they wanted to inherit their father's land. They would have to prove that their father had an inheritable estate when he died and that they were his next heir.