It is encouraging to see contenders introducing the issue of constitutional compliance into the campaign. However, none of them appear to yet have a firm grasp on the subject, including the two, Obama and Biden, who taught constitutional law in law schools.
The Founders did not, in general, use dictionary definitions of their terms. Dictionaries as we know them today were only just beginning to be written, and meanings of words were acquired by doing a lot of reading of works in which the words were used, and their meaning extracted by context, but seldom if ever defined.
It is therefore not surprising that Founder James Wilson, attempting to come up with a definition of "piracy", proposed "robbery and depredation on the high seas". However, from a more thorough examination of actual usages of the term, we can get something like this:
Piracy is a warlike act committed by a non-state actor, either a foreign actor against this country, or a domestic actor against another country.
But this covers what we are today calling "terrorism", and the Constitution, Art. I Sec. 8 Cl. 10, "The Congress shall have Power ... To define and punish Piracies and Felonies committed on the high Seas...", and we have a well-developed body of law on piracy.
We can then also see that the Constitution covers all possibilities, partitioning the set of warlike actions into those committed by state or non-state actors, those within the country by a domestic non-state actor (treason), and those committed between nations by a non-state actor (piracy).That also makes a warlike act committed by an official without a declaration of war or letters of marque and reprisal an act of piracy.