"nonsense," 1900, short for bunkum, phonetic spelling of Buncombe, a county in North Carolina. The usual story (attested by 1841) of its origin is this: At the close of the protracted Missouri statehood debates in the U.S. Congress, supposedly on Feb. 25, 1820, North Carolina Rep. Felix Walker (1753-1828) began what promised to be a "long, dull, irrelevant speech," and he resisted calls to cut it short by saying he was bound to say something that could appear in the newspapers in the home district and prove he was on the job. "I shall not be speaking to the House," he confessed, "but to Buncombe." Thus Bunkum has been American English slang for "nonsense" since 1841 (it is attested from 1838 as generic for "a U.S. Representative's home district").
MR. WALKER, of North Carolina, rose then to address the Committee on the question [of Missouri statehood]; but the question was called for so clamorously and so perseveringly that Mr. W. could proceed no farther than to move that the committee rise. [Annals of Congress, House of Representatives, 16th Congress, 1st Session, p. 1539]
"Well, when a critter talks for talk sake, jist to have a speech in the paper to send to home, and not for any other airthly puppus but electioneering, our folks call it Bunkum." [Thomas Chandler Haliburton, "Sam Slick in England," 1858]
see bunk (n.2). The North Carolina county was named for Edward Buncombe (1742–1778), North Carolina revolutionary leader and colonel in the American army.
"expose false or nonsensical claims or sentiments," 1923, from de- + bunk (n.2); apparently first used by U.S. novelist William Woodward (1874-1950), in his best-seller "Bunk;" the notion being "to take the bunk out of things." It got a boost from Harold U. Faulkner's "Colonial History Debunked" [Harper's Magazine, December 1925], which article itself quickly was debunked, and the word was in vogue in America in the mid-1920s. Related: Debunked; debunking.
Wets and Drys, Fundamentalists and Modernists, are busily engaged in debunking one another to the delight and edification of a public which divides its time between automobiling and listening-in. Is it art, or education, or religion that you prefer? You have only to get the right station and what you last heard about the matter will be cleverly debunked while you wait. [Carl Vernon Tower, "Genealogy 'Debunked," in Annual Reports of the Tower Genealogical Society, 1925]
It was, naturally, execrated in England.
The origin of to debunk is doubtless the same as that of American jargon in general — the inability of an ill-educated and unintelligent democracy to assimilate long words. Its intrusion in our own tongue is due partly to the odious novelty of the word itself, and partly to the prevailing fear that to write exact English nowadays is to be put down as a pedant and a prig. [letter to the editor, London Daily Telegraph, March 2, 1935, cited in Mencken, "The American Language"]
"large oblong bag," Middle English sak, from Old English sacc (West Saxon), sec (Mercian), sæc (Old Kentish) "large cloth bag," also "sackcloth," from Proto-Germanic *sakkiz (source also of Middle Dutch sak, Old High German sac, Old Norse sekkr, but Gothic sakkus probably is directly from Greek), an early borrowing from Latin saccus (also source of Old French sac, Spanish saco, Italian sacco), from Greek sakkos "bag (made of goat hair); sieve; burlap, large burlap cloak," which is from Semitic (compare Hebrew, Phoenician saq "sack, cloth of hair, bag, mourning-dress").
The wide spread of this word for "a bag" probably is due to the incident in the Biblical story of Joseph in which a sack of corn figures (Genesis xliv). In English, the meaning "a sack or sack material used as an article of clothing" as a token of penitence or mourning is from c. 1200. The baseball slang sense of "a base" is attested from 1913.
The slang meaning "bunk, bed" is by 1825, originally nautical, hence many slang phrases, originally nautical, such as sack duty "sleep;" the verb meaning "go to bed" is recorded from 1946. Sack-race (n.) is attested from 1805.