Source : Webster's Revised Unabridged Dictionary (1913)

Black Hand \Black Hand\ [A trans. of Sp. mano negra.]
   1. A Spanish anarchistic society, many of the members of
      which were imprisoned in 1883.

   2. A lawless or blackmailing secret society, esp. among
      Italians. [U. S.]

Source : WordNet®

Black Hand
     n : a secret terrorist society in the United States early in the
         20th century