E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
means songs strung together. The term was originally applied to the books of the Iliad and Odyssey, which at one time were in fragments. Certain bards collected together a number of the fragments, enough to make a connected ballad, and sang them as our minstrels sang the deeds of famous heroes. Those bards who sang the Iliad wore a red robe, and those who sang the Odyssey a blue one. Pisistratos of Athens had all these fragments carefully compiled into their present form (Greek rapto, to sew or string together; od, a song.)