This essay deals with two colour-related adjectives, badius and baietus, in the Medieval Latin documentary sources of Catalonia studied by the Glossarium Mediae Latinitatis Cataloniae (GMLC). The collection of documental testimonies has been conducted through the lexical database Corpus Documentale Latinum Cataloniae (CODOLCAT), a digital corpus of the Latin texts of this linguistic domain. These sources of notarial and juridical nature contain a considerable amount of colour adjectives, which usually serves to identify and differentiate lexical elements within the same referential class. One of the most attested colour adjectives is badius “bay, brown”, frequently documented with its variant baius and always referring to equines. There are also few occurrences of baietus “brownish”, a lexical innovation derived from badius. To refine their precise definitions, this study explores the forms and uses of both adjectives, taking into consideration the contexts in which they appear. Additionally, this study highlights the importance of the integration of digital tools into lexicographical research and emphasizes the need to incorporate insights from other linguistic domains to achieve a more comprehensive understanding of the words under analysis.