This article aims to examine the history of the emergence of legal terms and expressions used in the drafting of land deeds in Russian territories during the XIV–XV centuries. The content of land deeds from this period indicates that over the centuries in medieval Russia, a distinct legal language was formed through which transactions for the sale and purchase of land were formalized. Analyzing the terminology and speech patterns used in the drafting of land deeds not only allows for a deeper understanding of our ancestors’ perceptions of the sequence of actions accompanying the process of land alienation through sale and purchase but also traces the transformation of certain commonly used words from Old Russian and Old Church Slavonic into legal terms. The findings of the study suggest that the legal language of medieval Russian land deeds was shaped by the oral practice of concluding real estate transactions predominantly based on the lexicon and linguistic expressions of the Old Russian language. In conclusion, the study of the legal language of medieval Russian land deeds sheds light on the evolution of legal terminology and linguistic practices in the region. The incorporation of traditional linguistic elements into legal discourse underscores the importance of historical context in understanding legal language. Moving forward, continued research into the linguistic and legal aspects of medieval land deeds will contribute to our understanding of the legal history of Russia and its linguistic heritage.