Success in the development of cross-disciplinary connections between psychology and pedagogy in today's Russia depends on many factors, including understanding the historical traditions of theoretical comprehension of educational innovations. To identify the specific influence of psychology on didactic terminology from the early 18th century through the first half of the 20th century. The study was designed based on historiographic, diachronic, and synchronic methods, and context and content analysis of 129 texts (105 words with general usage frequency of 81,397 units were analyzed). It was found reasonable to split the development of psychological-didactic terminology into two stages: The instrumental stage (early 18th century - first half of 19th century) and the reference stage (second half of 19th century - first half of 20th century). The first stage was found to be characterized by psychological terms performing predominantly an instrumental function, that is, describing psychological factors that affect the effectiveness of training. The second stage featured the growing significance of psychological knowledge, not only in solving educational tasks, but also in explaining didactic patterns. During the first stage of development of psychological-didactic terminology, teachers frequently used the psychological terms "teaching", "ability", and "diligence", during the second stage - "teaching", "senses", and "development". Statistical methods were used to prove stable conceptual and terminological connections between psychology and pedagogy.