rossignoln.

Etymology: < Middle French, French rossignol nightingale (c1165 in Old French; also in Old French as losseignol (late 12th cent.), louseignol , lorsignol , lorseignol (all 13th cent.), etc.), ultimately < an unattested post-classical Latin form *lusciniolus , a masculine form corresponding to classical Latin lusciniola nightingale ( < luscinia nightingale (of uncertain origin; perhaps < luscus one-eyed (see louche adj.) + canere to sing (see chant v.) + -ia -ia suffix¹, on account of the bird's habit of singing in the dusk) + -ola -ola suffix¹). Compare Anglo-Norman russinol, russenole, roissenol (13th cent. or earlier), Old Occitan rossinhola (feminine; mid 12th cent.), rosinhol, roncinol (masculine; c1235), Catalan rossinyol (1272), Spanish †rossenor, †rossenol, (both a1250), †rossinol (c1250; now ruiseñor).The motivation for the development of the initial l- of the Latin forms to r- in the Romance languages is uncertain and disputed. It may reflect dissimilation of liquids in post-classical Latin *lusciniolus , although association with classical Latin russus red (see rouse adj.) has also been suggested, the nightingale's plumage being a reddish colour. Compare (beside classical Latin luscinia) post-classical Latin roscinia (7th cent. in a British source), ruscinia (9th cent.).