DROMEDARY,
a heavy, bundling Thief or Rogue. A purple Dromedary; a Bungler or a dull Fellow at Thieving.
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Entry taken from 1736 Canting Dictionary, by Nathan Bailey.
Dromedary in the 1811 Vulgar Tongue
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).