KING of the Gypsies,
the Captain, Chief, or Ringleader of the Gang, the Master of Misrule, otherwise called Uprightman. Vide Gypsies.
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Entry taken from 1736 Canting Dictionary, by Nathan Bailey.
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King of the Gypsies in the 1811 Vulgar Tongue
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).