A sea term for those days on which no meat is allowed to the sailors: the term is borrowed from the Banyans in the East Indies, a cast that eat nothing that had life.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Bantling * BaptizedNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes