Definition of "myth"

myth

/mɪθ/

noun
plural myths
1. A traditional story which embodies a belief regarding some fact or phenomenon of experience, and in which often the forces of nature and of the soul are personified; a sacred narrative regarding a god, a hero, the origin of the world or of a people, etc.
  Quotations
  Jacobsen's theory about the empty storehouse is still valid, for a myth never has one meaning only; a myth is a polyphonic fugue of many voices.
  1981, William Irwin Thompson, The Time Falling Bodies Take to Light: Mythology, Sexuality and the Origins of Culture, London: Rider/Hutchinson & Co., page 175
2. (uncountable) Such stories as a genre.
3. A commonly-held but false belief, a common misconception; a fictitious or imaginary person or thing; a popular conception about a real person or event which exaggerates or idealizes reality.
  Quotations
  Okay, okay, okay… First, of course, babies feel pain. How the fuck did we ever think otherwise⁉ But more importantly, the fact that painkillers are addictive was not a myth. It’s like a book of Greek mythology featuring the stories of Zeus, Sisyphus, Oedipus and Yanni. Come on! That last one is very real and it cannot be dismissed.
  2016, Tim Carvell [et al.], “Opiods”, in Last Week Tonight with John Oliver, season 3, episode 27, John Oliver (actor), Warner Bros. Television, via HBO
4. A person or thing held in excessive or quasi-religious awe or admiration based on popular legend
5. A person or thing existing only in imagination, or whose actual existence is not verifiable.
  Quotations
  As for Mrs. Primmins's bones, they had been myths these twenty years.
  1849, Edward Bulwer-Lytton, The Caxtons
  Living beyond the Omega-4 mass relay in the Terminus Systems, the mysterious Collector species is glimpsed so rarely as to be taken for a myth by most in galactic society. In reality, Collectors are human-sized insectoid bipeds and can resemble massive winged beetles. They are a terrifying force in the galaxy, responsible for the murder of hundreds of thousands.
  2010, BioWare, Mass Effect 2 (Science Fiction), Redwood City: Electronic Arts, PC, scene: Collectors Codex entry
6. An invented story, theory, or concept.