To debunk something is to take the bunk out of it—that bunk being “nonsense.” (Bunk is short for the synonymous bunkum, which has political origins.) Debunk has been in use since at least the 1920s, and it contrasts with synonyms like disprove and rebut by suggesting that something is not merely untrue but is also a sham—a trick meant to deceive. One can simply disprove a myth, but if it is debunked, the implication is that the myth was a grossly exaggerated or foolish claim.