Son of Zethus and Aedon: Homer, Odyssey 19.522 (web address 1).
The gloss -- likewise or similarly in other lexica (e.g. Hesychius iota1099) -- is uninformative, even misleading, as it stands. "Aedon [alpha 651] was racked with envy of her sister Niobe [nu 418], who rejoiced in the love of six sons and six daughters and, when trying to murder Sipylus, the eldest of them, she killed Itylus by mistake; whereupon Zeus transformed her into the Nightingale who, in early summer, nightly laments her murdered child" (Robert Graves, The Greek Myths 2.27).