Part or all of this entry has been imported from the 1913 edition of Webster’s Dictionary, which is now free of copyright and hence in the public domain. The imported definitions may be significantly out of date, and any more recent senses may be completely missing.
(See the entry for pendragon in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913.)
From Welsh pen, "head, chief, top" and dragon, "dragon; (figuratively) warrior"; borrowed from the Latin word dracō, plural dracōnēs, "dragon[s]" literally means "Chief-Dragon" or "Head-Dragon", but in a figurative sense, "chief leader", "chief of warriors", "commander-in-chief", "generalissimo", or "chief governor". 
pendragon (plural pendragons)
- A chief war leader, king, or dictator -- a title assumed by the ancient British chiefs when called to lead other chiefs.
- The dread Pendragon, Britain's king of kings. -- Tennyson.