Source : Webster's Revised Unabridged Dictionary (1913)

Pendragon \Pen"drag*on\, n.
   A chief leader or a king; a head; a dictator; -- a title
   assumed by the ancient British chiefs when called to lead
   other chiefs.

         The dread Pendragon, Britain's king of kings.
                                                  --Tennyson.

Source : WordNet®

pendragon
     n : the supreme war chief of the ancient Britons