At the turn of the twelfth century, a new term for emotions—accidentia anime—appeared in Latin with the introduction of the new medical corpus translated from the Arabic. The term first arrived from Monte Cassino where Constantine the African (d. 1098/9) translated the Isagogue by Ḥunayn Ibn Isḥāq and ‘Ali ibn al-’Abbas al-Majusi’s (Haly Abbas) Pantegni. Later translators of both medical and scientific treatises in Toledo, also working from the Arabic, employed the same term. Over the next three centuries, it became a terminus technicus specific to the medical field. Medical authors did use some alternative terms, which were de facto interchangeable, including passiones anime, passiones cordis, and motus anime or animi. These terms appeared in both medical and non-medical texts, in contrast to accidentia anime which became almost exclusively specific to the medical profession. 1 The choice of this particular term carried with it a trace of the theoretical debate within ancient Greek medicine about the nature of emotions. Late medieval medicine inherited the term, but with its specific tenor somewhat diminished. Still, as it became a professional medical term, it encapsulated key difficulties within the medical view of emotions. Highlighting these problems will also provide an instructive case study for the tenuous nature of the conceptualization of emotions in premodern thought more generally.