Based on the communicative and structural approaches, the author discusses the status of the term “visual sources in rare books of science” and related terms, as well as the visual sources classification and role in the rare books of science. The analysis, synthesis, systemic, structural, axiomatic, modelling and typology methods, as well as generalization and classification are applied. The visual sources make the subject of the study. Presenting visual sources in research works is a research method: the images are “to reveal” the textual component. The originality and value of the article lies in the author’s intent to define the place of visual sources and contained visual information within the terminological space of the rare science books. For this purpose, the author examines the definitions of visual sources in scientific literature and attempts herself to construct the term. The focus is made on the term “documentary visual source” that virtually is not used in scientific literature. In this context, the author discusses the terms “documentology” and “document”. Based on the related literature analysis, she concludes that no precise definition of visual sources classes and types exists. The author suggests sample classification of visual sources in science books and presents it in two tables. Further development of the definition would improve the terminological foundation of the visual sources. The goal of the article is to demonstrate the significance of the visual sources in the rare science books and their potential relevance for modern studies.