The Collaborative International Dictionary of English v.0.48:

Carbonaro \Car`bo*na"ro\, n.; pl. Carbonari. [It., a coal
   man.]
   A member of a secret political association in Italy,
   organized in the early part of the nineteenth centry for the
   purpose of changing the government into a republic.
   [1913 Webster]

   Note: The origin of the Carbonari is uncertain, but the
         society is said to have first met, in 1808, among the
         charcoal burners of the mountains, whose phraseology
         they adopted.
         [1913 Webster]