Q114. "I always thought that treason was the only crime defined in the Constitution, but a friend of mine insists it is not, though he refuses to say what the others are. Can you help?"
A. Sounds like your friend isn't being as forthcoming as you would think a friend would be. However, I think that your friend is confusing "definition" with "mention." It is certainly true that treason is the only crime that has its minimum standard set in the Constitution itself, in Article 3, Section 3. There, treason is defined and the standard for conviction is set. No other crime is treated so thoroughly. However, Article 1, Section 8, Clause 6 specifically mentions counterfeiting, which may be what your friend is thinking of. Other clauses in that section mention much more nebulous crimes, such as "Piracies and Felonies committed on the high Seas" and the like.