One who is always foretelling some accident or misfortune: an allusion to the croaking of a raven, supposed ominous.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Crispin’s Lance * CroakumshireNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes