A mode of signing remonstrances practised by sailors on board the king’s ships, wherein their names are written in a circle, so that it cannot be discovered who first signed it, or was, in other words, the ringleader.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Roundheads * Round SumNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes