In the last third of the 19th century, Romance philology revealed that in some dialects of the Sardinian area and Northern Italy the name of “Thursday” was feminine. This led to conclude that, in parallel to the term Iouis, a variant *iouia had also existed in Latin. The subsequent publication of the Latin Oribasius by A. Molinier brought this feminine form to light for the first time, attested in a passage on sciatica. The article reports a second example of the variant iouia. It appears twice in a still unpublished medical recipe preserved in a 9th-century manuscript of North-Italian origin. The hypothesis that this feminine name for “Thursday” must have been common in northern Italy in Late Antiquity and the early Middle Ages is thus gaining strength.