Green’s Dictionary of Slang

chouse n.

also chowse
[Turkish chiaus, chaus, an official messenger. The link here comes either from the fleecing in 1609 of some Turkish and Persian merchants by an agent or chiaus of Sir Robert Shirley (the OED rejects this for lack of corroborative evidence), or by the philologist Thomas Henshaw’s remark that a Turkish messenger ‘is little better than a fool’, a dictum that he claimed was sufficient proof of an ety.]

1. (also chouser) a cheat, a swindler.

[UK]Jonson Alchemist I ii: What do you think of me? That I am a chiause? [...] As one would say, do you think I am Turk?
[UK]Ford Lady’s Trial II i: Gulls, or Moguls, Tag, rag, or other, hogen-mogen, vanden, Skip-jacks, or chouses.
[UK]Wycherley Love in a Wood I i: He a dancing-master, he’s a chouse, a cheat, a meer cheat.
[UK]M.P. Andrews Better Late than Never 7: Dramatis Personae [...] Sir Charles Chouse.
[Ind]G.F. Atkinson Curry & Rice (3 edn) n.p.: Chouse Lall, the great Koprawallah , is eternally at her house. I see his big bundles blocking up her door every day.
Plain or Ringlets? (1926) 3: Chousey’s Hotel, so famous for charges [...] Chousey, however, carries things off with [...] such an elegant air, that it is almost a pleasure to be imposed upon by him.
D.C. Murray Hearts II 78: The chousers and borrowers mistook him for a fool, naturally enough.

2. a dupe, a gullible victim.

[UK]S. Butler Hudibras Pt III canto 3 line 531: Sillier than a sottish chowse, / Who, when thief has robb’d his house, / Applies himself to cunning men, / To help him to his goods agen.

3. a swindle, a confidence trick.

[UK]J. Kersey Dictionarium n.p.: Chowse, a Cheat, Trick, or Sham.
[UK]Johnson Dict. Eng. Lang. (1785) n.p.: Chouse, a trick or sham.
Mrs. Parr in Longman’s Mag. Apr. 639: ‘I say, what a chouse for Adda!’ roared Freddy delightedly.