And the section of the Constitution where it is defined?
It doesn't really matter, since no matter what definition you use that was extant during the time of the founders, none vindicate Ted Cruz.
Unless he was naturalized after birth, I assume you have no proof he was, the fact that he is a US citizen can only mean he was at birth. If citizen at birth isn't natural born, then what is it?
Where is "speech" defined? Where is "arms"?
Unless he was naturalized after birth
By definition, if congress has to pass legislation to make you a citizen at birth, then you are a naturalized citizen, even at birth. Congress only has powers over naturalization. It has no power over natural born citizens.