rossignol

nightingale; picklock, skeleton key; piece of junk

“chanter comme un rossignol”

From Old Occitan rossinhol (cf. Catalan rossinyol), from Vulgar Latin *lusciniolus, masculine diminutive of Latin luscinia (“nightingale”). According to De Vaan, "might be explained with haplology from *lusci-cania (“singing in the night; blind singer”), but this is conjecture.