Source : Webster's Revised Unabridged Dictionary (1913)

Triumvirate \Tri*um"vi*rate\, n. [L. triumviratus: cf. F.
   triumvirat.]
   1. Government by three in coalition or association; the term
      of such a government.

   2. A coalition or association of three in office or
      authority; especially, the union of three men who obtained
      the government of the Roman empire.

Source : WordNet®

triumvirate
     n : a group of three men responsible for public administration
         or civil authority