Nonsensical words used by jugglers, previous to their deceptions, as a kind of charm, or incantation. A celebrated writer supposes it to be a ludicrous corruption of the words hoc est corpus, used by the popish priests m consecrating the host. Also Hell Hocus is used to express drunkenness: as, he is quite hocus; he is quite drunk.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Hocking * HodNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes