Green’s Dictionary of Slang

1. (US) a counterfeiter, thus koniacking, counterfeiting.

1827		Commercial Advertiser (N.Y.) 26 Jan. 2/3: Our readers are not perhaps aware that there is such a term in the English language as a Coneyacker. Indeed we cannot wonder at their ignorance, as, until this morning, we never ourselves [...] had heard of or even imagined such a term. It is, we believe, solely a police term, and signifies a dealer in counterfeit money.
1838		N.Y. Daily Express 7 Dec. 2/3: [A counterfeiter’s] gang are known in Canada by the title of koniackers, and among them, in conversation, they have adopted a set of slang phrases, such as ‘smashing’ (counterfeiting) ‘conack’ [sic] or ‘pictures’ (counterfeit notes) ‘bogus’ (counterfeit coin) &c.
1841		N.Y. Herald 13 Dec. 2/5: Another ‘Cogniacker’ Arrested. Artemas, Brundige, a well known ‘Cogniaker’ or manufacturer of counterfeit and altered notes.
1842		N.Y. Herald 25 May 2/6–3/1: A notorious member of the gang of ‘Konigackers,’ [sic] known as ‘Joe Wyanocky’.
1846		Nat. Police Gaz (NY) in Van Every (1931) 1: The notes engraved by Parkes were always at premium among the subordinate konyackers working in [...] various states.
1848		Bartlett Dict. Americanisms 396: Coniacker, a counterfeiter of coin.
1851		‘Greenhorn’ [G. Thompson] Bristol Bill 58/2: Ashley attempted to go bail for the notorious Smith Davis, his brother-in-law, (and King of the Koneyackers.
1860		Dly Exchange (Baltimore, MD) 27 Feb. 2/3: In police parlance, a counterfeiter is termed a ‘koniacker’.
1865		Plymouth Wkly Democrat (IN) 5 Jan. 1/5: Horse jockies, horse thieves [...] buffers, bummers [...] bravos and panderers [...] bludgenors, bounty jumpers, koniackers, knucks [and] pocketbook stuffers.
1867		Nat. Police Gaz. (NY) 30 Nov. 2/4: Manson, a son of the celebrated Clock Manson, of ‘koniacking’ fame.
1872		G.P. Burnham Memoirs of the US Secret Service 85: Bill became one of the leading ‘queersmen’ in New York state. He made the acquaintance [...] of almost every ‘koniacker,’ ‘boodle-carrier’ and dealer, large or small, in this part of the country.
1872		Schele De Vere Americanisms 296: False coins, the makers of which are curiously called coniackers.
1881		Trumble Man Traps of N.Y. 41: Real ‘koniackers,’ as we term counterfeiters, never advertise for people to handle their money.
1885		Ledger (Noblesville, IN) 14 Aug. 6/2: ‘There are four or five “coniackers” in here now’.
1889		(ref. to 1855) Eve. Star (Washington, DC) 12 Aug. 3/7: Away back in 1855 Driggs kept a country store [...] which was used as headquarters for a gang of ‘koniackers’.
1890–1904		Farmer & Henley Sl. and Its Analogues II 167/2: Coniaker [...] (thieves’), – a counterfeiter; smasher; or ‘queer-bit’ faker.
1895		C. Crowe Aus. Sl. Dict. 43: Koniacker, a counterfeiter.
1906		Cameron Co. Press (PA) 29 Mar. 6/3: The stranger confided his criminal history and desire to handle ‘coney’. He combined preaching with larceny [...] and those of ‘koniacker’ .
1910		Iron Co. Register (MO) 10 Nov. 6/1: ‘Big Bill’ the Koniacker, one of the foremost wholeseale dealers in ‘queer’.
1935		A.J. Pollock Und. Speaks 24/2: Coniacker, a counterfeiter.

2. attrib. use of sense 1.

1842

N.Y. Herald 15 Apr. 2/3: One of the ‘Kogniacker’ gang named George Owens, alias McKerkin, was jugged yesterday for attempting to pass a $3 counterfeit note.