In early eleventh century Zaragoza, the eminent Jewish scholar Abū l-Walīd Marwān ibn Janāḥ wrote a glossary containing almost 1100 entries, entitled Kitāb al-Talkhīṣ. This important text, considered lost until recently, contains Arabic and foreign-language names of simple drugs, weights, measures, and other medical terms. In the present volume, the Kitāb al-Talkhīṣ is edited and translated for the first time by Gerrit Bos and Fabian Käs. In detailed commentaries, the editors identify the substances mentioned in the Talkhīṣ. They also elaborate on the role of the text in the history of Arabic glossaries concerned with medical nomenclature. Special attention is paid to Ibn Janāḥ’s Ibero-Romance phytonyms, analysed in depth by Mailyn Lübke and Guido Mensching.