jordain, n. — Green’s Dictionary of Slang

jordain n.

[ety. unknown; ? f. use of ‘go over the Jordan’ as euph. for die; such a blow might kill the recipient; ? play on Genesis XXXII:10 ‘With my staff I passed over this Jordan; and now I am become two bands’]

(UK Und.) a blow with a staff.

c.1698		B.E. Dict. Canting Crew n.p.: Jordain c. a great Blow or Staff [...] I’ll tip him a Jordain if I transnear, c. I will give a Blow with my Staff if I get up to him.
1719		A. Smith Lives of Most Notorious Highway-men, etc. (1926) 207: Jordain, a great blow or staff. I’ll tip him a jordain, if I trans-near, i.e., I’ll give him a blow with my staff, if I come near.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: [as cit. 1719].
1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum [as cit. 1719].
1859		Matsell Vocabulum 47: jordain A blow. ‘I’ll tip the Jack Dove a jordain on the jazey, if I transear him,’ I’ll hit the mean fellow with my club on his big nose, if I get near him.