It often implies a story that is:
* Traditional: Passed down through generations and considered part of a culture's history or belief system.
* Symbolic: Containing deeper meanings and lessons about human nature, the world, or the divine.
* Fictional or mythical: Not necessarily historically accurate, but representing a truth or understanding that may not be literally true.
Therefore, "myth-" usually refers to something that is legendary, symbolic, or even fictional, but often carries cultural and philosophical significance.