Abstract
<jats:p>Although criminalistics is not considered to be a young science, discussions regarding its subject continue to this day. Both the founders of criminalistics and contemporary researchers have expressed their opinions on this issue. In spite of this, the authors would like to draw attention to one important aspect of the teaching on the subject of criminalistics which, in spite of its methodological significance, has not yet been adequately and fully reflected in scientific studies and remains practically unexplored. It is the issue of formulating and using key concepts, categories and terms in the criminalistic theory on the subject of science, primarily, the unity of its language, the use of shared concepts, categories and terms. It should be recognized that such questions, fundamental for the criminalistic cognition of the subject of science, as the correlation between is subject and object, the subject of scientific cognition and the subject of scientific research, or the subject of science and the subject of a study course, still remain unanswered. There is also ambiguity in the assessment of the composition of phenomena included in the subject of criminalistics, and those reflected in its definitions.</jats:p>