Green’s Dictionary of Slang

1. a lawyer.

c.1700		Street-robberies Consider’d 32: Jet, Lawyer .
1725		New Canting Dict. n.p.: jet a Lawyer.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. 1725].
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
a.1790		H.T. Potter New Dict. Cant (1795).
1809		G. Andrewes Dict. Sl. and Cant.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1835		G. Kent Modern Flash Dict.
1846		Swell’s Night Guide 123/1: Jet, a lawyer.
1859		‘Scene in a London Flash-Panny’ Matsell Vocabulum 99: But how did you hare it to Romeville, Bell, for I suppose the jets cleaned you out?
1881		Trumble Sl. Dict. [as cit. 1859].

2. a priest or parson .

1846		Swell’s Night Guide 123/1: Jet autem, a parson.
1903		(ref. to 1870s) Eve. Post 26 Nov. 6/3: They all dodge the Jet Autem, and sneak down the slade / To appear arm-in-arm at the Monkey’s Parade.