Etymology From jack + leg. Compare blackleg (“a person who replaces striking workers; a cheater”) and such expressions as jack of all trades, every man jack.
1841, Letter to the editor, The Southern Planter, Volume I, No. 1, January 1841, p. 12, The next year I had a projecting kind of jack leg carpenter, from Hanover, living with me in the capacity of overseer […]
1941, Martha Colquitt, Interview published in Slave Narratives, Library of Congress Project, Volume 4: Georgia Narratives, Part 1, Grandma didn’t think chillun ought to see funerals, so de first one I ever seed, wuz when ma died two years atter de War wuz done over. A jackleg colored preacher talked, but he didn’t have sense ’nuff to preach a sho’ ’nuff sermon.
2 more examples
1957, Frederik Pohl and C. M. Kornbluth, Wolfbane, Chapter 11, in Galaxy Science Fiction, He was a doer, not a thinker; his skills were the skills of an artisan, a tinkerer, a jackleg mechanic.
At the gas station on the corner, a jackleg work crew was attaching plywood to the windows.2010, Jabari Asim, “Day Work”, in A Taste of Honey, New York: Broadway Books, page 189:
The little nosy reporter with the hair was fair crazy to come, but McGinty gets a jackleg doctor to examine him an’ swear that he’s sufferin’ from spatulation o’ the medulla oblongata, housemaid’s knee, and the hives.1911, Peter B. Kyne, chapter 14, in Captain Scraggs or The Green-Pea Pirates, New York: Grosset & Dunlap:
Villard’s great fortune should not be allowed to “dangle” in plain sight of “jack-leg lawyers,” while he, Parkins, awaited final results of the proceedings.1921, Sumner Charles Britton, chapter 4, in Dreamy Hollow, New York: World Syndicate Company, pages 49–50:
1 more example
When I went to the so-called authorities for help I ran into jackleg politicians, wheeler-dealers, henchmen, finaglers and wire-pullers.1988, Joyce Carol Thomas, chapter 1, in Journey, New York: Scholastic, page 27:
The train is late […]. ¶ “Well, if I come to such a place as this I must expect a jackleg railroad […].”1889, John McGovern, chapter 12, in David Lockwin: The People’s Idol, Chicago: Donohue:
“With the first good rain the entire jackleg contraption might collapse around my ears […]”1989, Jack Vance, chapter 7, in Madouc, Novato, California: Underwood-Miller, page 168:
2 more examples
2005, William Hoffman, Lies, Montgomery, Alabama: River City Publishing, Chapter 23, p. 226, Driving the secondhand Chevy pickup, he visits not only major car dealerships but also every jackleg garage he happens upon in dusty sun-blasted towns of the Deep South.
[…] he went first to the barn […] and made a jackleg bed with hay and an old mule blanket.2012, Stephen King, The Wind Through the Keyhole, New York: Simon & Schuster, page 176:
jackleg
noun
Etymology From jack + leg. Compare blackleg (“a person who replaces striking workers; a cheater”) and such expressions as jack of all trades, every man jack.
1
A type of drill operated by means of compressed air.
2
US An amateur; an untrained or incompetent person.
[…] I, gentlemen and ladies, are a rale Scientificky! I ain’t none of your jack-legs.1846 July, Editor’s Table, The Knickerbocker, volume 28, number 1, page 87:
Would the reader care to know something about the story which I pulled out? He has been told many a time how the born-and-trained novelist works; won’t he let me round and complete his knowledge by telling him how the jack-leg does it?1894, Mark Twain, The Tragedy of Pudd’nhead Wilson and the Comedy Those Extraordinary Twins, Hartford, Connecticut: American Publishing Company, page 311:
2 more examples
“Lady,” he said, jerking his short arm up as if he could point with it to her house and yard and pump, “there ain’t a broken thing on this plantation that I couldn’t fix for you, one-arm jackleg or not […].”1955, Flannery O’Connor, “The Life You Save May Be Your Own”, in A Good Man Is Hard to Find and Other Stories, New York: Harcourt Brace Jovanovich, published 1977, page 58:
1999, David Horsley, Into the Wind, Houston, Texas: Winedale Publishing, “Tops for Trees,” p. 180, If it were up to me, we’d have a city ordinance against incompetent pruning of trees. You need a permit to unclog a sewer or fix a light switch, but any jackleg with a chainsaw can climb up a ladder and undo in five minutes what Mother Nature took decades to accomplish.
3
US A shyster or con artist; a gambler who cheats; a generally dishonest or reprehensible person.
“[…] we ain’t called on to believe every smooth-talking jackleg who wanders in here.”1985, Wesley Ellis, chapter 9, in Lone Star and the California Oil War, New York: Jove, page 121:
“Guess what th’ low-down jackleg has done now.”1997, Jan Karon, chapter 7, in Out to Canaan, New York: Viking, page 113: