A more thorough explanation:

Term: extraneus
Definition: Extraneus means a person who is not from the same country or family as the person they are associated with. It can refer to someone who is foreign-born or an heir who is not related to the person who left them something in their will.
Examples: An example of an extraneus would be someone who was born in France but now lives in the United States. Another example would be if someone left their inheritance to a distant cousin who they had never met before, that cousin would be considered an extraneus. These examples show how extraneus refers to someone who is outside of the usual group or family.