Green’s Dictionary of Slang

gammy adj.1

[according to Mayhew, London Labour and the London Poor (1862), Welsh gam, crooked, queer]

1. (UK Und.) bad; usu. in combs. below.

[UK]Liverpool Mercury 14 Jan. 38/2: Now in summer, at Hull, me and three more men might get six to eight pounds a week a piece, but we had to [...] keep a sharp look out, for its very gammy (3) [...] (3) Gammy. A town where they take them sharoer than others.
[UK]H. Mayhew Great World of London I 6: The slang term ‘gammy’ (bad) comes fom the Welsh gam, crooked, queer.
[UK]Hotten Dict. of Modern Sl. etc. 44: gammy, bad, unfavourable, poor tempered. [...] gammy-vial (Ville), a town where the police will not let persons hawk.
[UK](con. 1840s–50s) H. Mayhew London Labour and London Poor I 218/2: There are generally two or three persons in a village reported to be ‘gammy,’ that is (unfavourable).
[Aus]Melbourne Punch ‘City Police Court’ 3 Oct. 234/1: The Mayor. – You are as gammy a gonnof as ever I saw, and I expect your doxy’s as bad.
[UK]Liverpool Mercury 2 Dec. 3/2: No villages that are any way ‘gammy’ are ever mentioned.
[UK]Sl. Dict. 173: Gammy bad, unfavourable, poor tempered. Those householders who are known enemies to the street folk and tramps are pronounced by them to be gammy Gammy-vial (Ville) a town where the police will not let persons hawk.
[UK]Manchester Courier 28 Jan. 10/6: Our hero was taken before the ‘gammy’ parson-magistrate.
[Scot]Dundee Courier (Scot.) 8 Sept. 7/3: There were several ‘travellers’ in the lodging house, and all [...] assured me that the town was not ‘gammy,’ and that I could ‘call’ it without fear from one end to the other.
[UK]Hampshire Teleg. 31 Mar. 11/5: [A petition] with ‘gammy monekurs,’ or forged names, cannot be had for less than half-a-crown.
[UK]Clarkson & Richardson Police! 236: Manufacturers of spurious soaps, oils, and of many other deceptive commodities [...] in their own slang, are described as ‘gammy vendors’.
[UK]Shields Dly Gaz. 19 July 5/1: He was travelling through Berkshire, a county well known to the fraternity for being ‘gammy’.
[Aus]Crowe Aus. Sl. Dict. 31: Gammy, bad, forced, spurious, etc.
[Aus]Sydney Sportsman (Surry Hills, NSW) 6 Mar. 4/1: The faking fighters [...] simply transferred their gammy game to the rival club.

2. (UK Und.) fake, counterfeit.

[UK]Sunderland Dly Echo 1 June 2/5: On his waistcoat breast dangled what in classical vernacular is called a ‘gammy 18 carat gold chain’.
[Aus]Sydney Sl. Dict. (2 edn) 4: Gammy - Bad. Gammy Stuff - Spurious medicine and other articles.
[UK]Hants. Teleg. 31 Mar. 11/5: A petition [...] with ‘gammy monekurs’, or forged names, cannot be had for less than half-a-crown.
[Scot]Eve. Teleg. (Dundee) 15 Mar. 11/2: I am often defrauded by people who put ‘gammy’ money into my collection box.

In compounds

gammy lour (n.) (also gammy lower, ...lowr)

(UK Und.) counterfeit coins, thus gammy lour pitcher, one who passes counterfeit.

[UK]H. Brandon Dict. of the Flash or Cant Lang. 168: Schofel pitchers work the bulls and gypsies make and plant the gammy-lowr swags.
[UK]‘Ducange Anglicus’ Vulgar Tongue 39: Schofel pitchers work the bulls and gypsies make and plant the gammy-lowr swags.
[UK]Hotten Dict. of Modern Sl. etc. 60: ‘gammy lour,’ bad money.
[UK]Hotten Sl. Dict. [as cit. 1859].
[UK]Sl. Dict. 173: gammy sometimes means forged, as [...] gammy lowr, counterfeit coin.
[Aus]Sydney Sl. Dict. (2 edn) 4: Gammy Lowr - Bad money [...] Gammy Lowr Pitchers - Utterers of base coin.
[UK]Clarkson & Richardson Police! 321: Bad money ... Gammy lower.
gammy monniker (n.) (also gammy moneker, ...monekur)

(UK Und.) a forged signature.

[UK]Hotten Dict. of Modern Sl. etc. 44: gammy sometimes means forged, as gammy-moneker, a forged signature.
[UK](con. 1840s–50s) H. Mayhew London Labour and London Poor I 313/2: Ditto, with gammy monekurs (forged names).
[UK]Sl. Dict. 173: gammy sometimes means forged, as ‘gammy-monniker,’ a forged signature.
gammy stuff (n.)

(UK Und.) spurious soap or medicine.

[UK]H. Brandon Dict. of the Flash or Cant Lang. 168: The crocusses pad through every wild, to fence the gammy stuff.
[US]Matsell Vocabulum 39: gummey-stuff [sic] medicine.
[UK]Sl. Dict. 173: gammy sometimes means forged, as [...] gammy stuff, spurious medicine.
[Aus]Sydney Sl. Dict. 10/2: The padding ken of Sally Flicks, who’s got a new moniker, which is Lushing Loo, is full of bug-hunters, and shallow coves, and fellows on the high fly. The two crocuses are gadding the pad to fence their gammy stuff.
[Aus]Crowe Aus. Sl. Dict. 34: Gummey, [sic] medicine.