Green’s Dictionary of Slang

1. cant, criminal slang.

1530		Palsgrave Lesclarcissement de la Langue Francoyse n.p.: Verbes: Speake a pedlars frenche, or a gybberishe or any contrefait language, Ie iargonne [...] They speke a pedlars frenche amongst themselfe: ils iargonnet entre eulx.
c.1535		R. Copland Hye way to the Spyttel House Eiii: And thus they babble, tyll theyr thryft is thyn / I wote not what with their pedlyng frenche.
c.1566		Harman Caveat for Common Cursetours in Viles & Furnivall (1907) 23: As far as I can learne or understand by the examination of a number of them their languag – which they terme peddelars Frenche or Canting – began but within these xxx yeeres, or lytle above; and that the first inventer therof was hanged, all save the head; for that is the fynall end of them all, or els to dye of some filthy and horyble diseases.
1577		W. Harrison Description of Britain in Ribton-Turner (1887) 466: In counterfeiting the Egyptian rogues they have devised a language among themselves, which they name Canting but other pedler’s French a speach compact thirtie yeares since of English, and a geat number of od words of their owne devising [...] such is it as none but themselves are able to understand.
1598		Florio Worlde of Wordes in Farmer & Henley Sl. and Its Analogues V 158/1: Gergare, to speak fustian, pedlers french, or rogue language.
1608		Dekker Belman’s Second Nights Walk B3: It was necessary, that a people [...] daily practising new and strange Villainies, should borrow to themselues a speech, which none but themselues should vnderstand; for that cause was this Language, (which some call Pedlers French) Inuented.
c.1616		Beaumont & Fletcher Faithful Friends I ii: ’Twere fitter / Such honest lads as myself had it, that instead / Of pedlar’s French gives him plain language for his money.
1622		Massinger Virgin-Martyr II i: Why, fellow Angelo, we were speaking in pedlar’s French, I hope.
1630		J. Taylor ‘Taylors Revenge’ in Works (1869) II 146: Instructing thee in the braue Canting tong / And how in Pedlers French to sing a song.
c.1640		J. Shirley Captain Underwit II ii: One rime more and you undo my love for ever. Out upon’t! pedlars French is a Christian language to this.
1664		T. Jordan ‘A Canting Rogue Parallel’d with a Phanatick’ in A Royal Arbor 71: Thus is poor Colter poison’d with a drench / Made of Law Latin, and low Pedlar’s French.
1672		J. Phillips Maronides (1678) VI 36: While Priest invoking Tawnie wench, / Mumbled his Pray’rs in Pedlars French.
a.1674		‘Touch and Go’ in Ebsworth Roxburghe Ballads (1891) VII:2 486: Whilst they together were, the Taylor he came there, / And spake his Pedlar’s-French, that he would have a wench.
1681		W. Knight Vox Stellarum 152: [T]he Planets or Stars of Heaven did not whisper nor gibber in Pedlar's French, but speak with a loud Voice, and in plain Language.
c.1698		B.E. Dict. Canting Crew n.p.: Pedlar’s-French, a sort of Gibrish or made language easy to be Learnt and understood, used by Gypsies, &c. Also the Beggers Cant.
1712		P. Motteux (trans) Don Quixote 801: All this was Greek, or Pedlar's French to the Country-men;.
1725		New Canting Dict. [as cit. c.1698].
1741		[title] Canting Academy, or the Pedlar’s-French Dict.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue iii: The Vulgar Tongue consists of two parts: the first is the Cant Language, called sometimes Pedlar’s French, or St. Giles’s Greek.
1811		Lex. Balatronicum.
1822		(con. early 17C) W. Scott Fortunes of Nigel II 303: A gamester, one who deals with the devil’s bones and the doctors, and not understand Pedlar’s French!
1834		W.H. Ainsworth ‘Preface’ to Rookwood (1849) xxi: Its meaning must be perfectly clear [...] to the practised patterer of Romany or Pedlar’s French.
1867		(con. 1600s) M. Lemon Leyton Hall I 234: They be cant names for such thieves [...] It was called, I remember, Pedlar’s French.
1868		Liverpool Mercury 2 Dec. 3/2: A mixture of gypsy, old English, newly-coined words, and cribbing from any foriegn language, mixed and jumbled together, formed what has been known as the ‘canting language,’ or ‘pedlars’ French’.
1889		Reynolds’ Newspaper 28 July 6/3: The language he uses is barbarous, as being but a dialect of pedlars French or Egyptian.
1897		C. Whibley A Book of Scoundrels 31: His intimate acquaintance with the vagabonds of speech enabled him to compile a dictionary of Pedlar’s French.

2. any incomprehensible language.

1887

H. Caine Deemster n.p.: Kidnapped? No such matter... What pedlar’s French! [OED].