Source : Webster's Revised Unabridged Dictionary (1913)

Myth \Myth\, n. [Written also {mythe}.] [Gr. my^qos myth, fable,
   tale, talk, speech: cf. F. mythe.]
   1. A story of great but unknown age which originally embodied
      a belief regarding some fact or phenomenon of experience,
      and in which often the forces of nature and of the soul
      are personified; an ancient legend of a god, a hero, the
      origin of a race, etc.; a wonder story of prehistoric
      origin; a popular fable which is, or has been, received as
      historical.

   2. A person or thing existing only in imagination, or whose
      actual existence is not verifiable.

            As for Mrs. Primmins's bones, they had been myths
            these twenty years.                   --Ld. Lytton.

   {Myth history}, history made of, or mixed with, myths.

Source : WordNet®

myth
     n : a traditional story accepted as history; serves to explain
         the world view of a people