A traditional or legendary story, usually concerning some being or hero or event, with or without a determinable basis of fact or a natural explanation, especially one that is concerned with deities or demigods and explains some practice, rite, or phenomenon of nature (Dictionary.com).
From Fr. mythe and directly from M.L. mythus, from Gk. mythos "speech, thought, story, speech, account," of unknown origin.
Osturé, from Ar. usturat, from Gk. historia, → history.