An Exchange Alley term for one who buys stock on speculation for time, i.e. agrees with the seller, called a Bear, to take a certain sum of stock at a future day, at a stated price: if at that day stock fetches more than the price agreed on, he receives the difference; if it falls or is cheaper, he either pays it, or becomes a lame duck, and waddles out of the Alley. See Lame Duck and Bear.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
See also the definition in Nathan Bailey's 1736 dictionary of canting and thieving slang.
Bulker * Bull-1Nathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes