E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
means simply something to be read as part of the divine service. The narratives of the lives of saints and martyrs were so termed from their being read, especially at matins, and after dinner in the refectories. Exaggeration and a love for the wonderful so predominated in these readings, that the word came to signify the untrue, or rather, an event based on tradition.
A myth is a pure and absolute imagination; a legend has a basis of fact, but amplifies, abridges, or modifies that basis at pleasure.Rawlinson: Historic Evidences, lecture i. p. 231, note 2.