(1):
(n.) 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):
(n.) A person or thing existing only in imagination, or whose actual existence is not verifiable.