A beautiful word, I think, meaning 'like, or pertaining to a nightingale'. Etymologically it derives from Philomela, a princess of Athens who was raped by her brother-in-law Tereus. He cut out her tongue to silence her; the gods transformed her into a nightingale, so that she could sing beautifully for ever.
In Ovid's Metamorphoses Philomela's defiant speech is rendered as (in translation) "Now that I have no shame, I will proclaim it. / Given the chance, I will go where the people are, / Tell everybody; if you shut me here, / I will move the very woods and rocks to pity. / The air of Heaven will hear, and any god, / If there is any god in Heaven, will hear me."