Of course the Constitution isn't a dictionary.
Its terms have to be defined by intent.
And divining intent by saying: "just check Vattel or the 1790 Naturalization Act or the comments made by Judge A in case X or by majority B in case Y" doesn't solve the issue.
A hard and fast definition covering all the angles of the issue has yet to be offered by any "authority", or found in the writings of any Founder, or in the legislation of any Congress or the decisions of any court.
The definition covering all the angles of the issue carved in stone by George Washington himself and placed in the cornerstone of the White House for safe keeping would not enough for some.