Except it's not. It's basic knowledge of the English language.
Myth - definition
1: 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.
2: stories or matter of this kind:realm of myth.
3: any invented story, idea, or concept:His account of the event is pure myth.
4: an imaginary or fictitious thing or person.
5: an unproved or false collective belief that is used to justify a social institution.
And you sure as ducks swim ain't using the first definition.