Abstract: Jabir ibn Hayyan, is one of the greatest figures in Arab culture and in applied chemistry. He contributed to the formation of chemical terminology in the Middle Ages, the vast majority of which still continues to function in modern chemistry and medicine. The article discusses the significant contribution of the Arab thinker in the formation of the Arabic medieval scientific chemical discourse at the first stages of its formation, which was revealed on the basis of Aristotle's methodological principles, the language of alchemy, translation from ancient Greek and Egyptian texts into Arabic. This led to the synthesis of ancient scientific concepts and the emergence of Arabic scientific terms denoting specific concepts of chemistry and the emergence of the first classification of substances and medicines. Continuous experimental studies of substances led to the emergence of new names of previously unknown substances, such as alkali, nitric acid, etc. In this paper, the achievements of Arab medieval scientists in applied chemistry were characterized and the main chemical vocabulary used in the description of various substances was analyzed. On the basis of the collected material, attempts were made for the first time to generalize the achievements of the Arab chemist using modern methods of studying terms and concepts. The attention is drawn to the inner side of the Arabic scientific term, which constitutes its conceptual base and the definition of which largely depends on the regulation of linguistic activity in the sphere of alchemy.