Abstract
This article studies the discursive expression of definitions in a series of Medieval and Renaissance medical texts written in Spanish. Since lexicographers are not the only ones in charge of writing definitions, we consider that by examining other types of texts, rather than just dictionaries, will help us gain a better understanding of this practice in the history of Spanish written traditions. Although it is difficult to establish a classification by strictly using the criteria designed for modern lexicography, it is possible to determine tendencies within these Spanish medical texts, such as the formulation of definitions using synonyms and glosses, hyperonyms, etymological information and reference to authorities.