A man under sentence of transportation; alluding to the convicts at Woolwich, who are principally employed in wheeling barrows full of brick or dirt.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Barrel Fever * Bartholomew BabyNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes