Simply not true, as I've already explained. There is no such definition in US law.
The Supreme Court told us the definition of natural born citizen is extraconstitutional. It is not defined by U.S. law or the Constitution, and they proceeded to say that without doubt, it is someone born in a country to parents who are its citizens, citing the Vattel definition nearly word for word.
Nor is there a definition for things like "commerce", but there is a commonly understood meaning for the term, at the time it was committed, and historcal reference to support a claim that the understanding that children born on US soil to foreign parents were not "natural born citizens" at that time.