The article warns readers interested in the specialised communication against an uncritical adoption of the term professional language, which is often used in the extensive literature on the subject without care for terminological precision. The lack of awareness of the meaning of the term professional language leads to negative consequences in linguistic argumentation, such as the neglect of the current state of research in general linguistics, the contamination of the scientific term by its naive understanding in everyday communication between laypersons, or the identification of language and its use, which is a serious methodological deficiency. The reader of the specialised literature might therefore, without sufficient linguistic knowledge, mistakenly take the contents presented in the reading as self-evident and corresponding to the current state of knowledge. In the first part of the article, the aforementioned sources of interpretative dangers in reading are pointed out, using the history of research as an example. Subsequently, the reader is offered some constant points of reference fur further interpretation, which allow to recognise a stylistic-functional variety of ethnic language in the concept of professional language, including phenomena that go beyond the reduction of professional language to mere terminology. The author also pointed out the forms of acquisition and existence of the so-called professional languages, as well as the distributional features that distinguish them from other functional-stylistic varieties of the ethnic language. In conclusion, their peculiarity was highlighted, arising from the need for precise naming of phenomena and processes in the field of human activity, which is concluded by the specificity of the field; from the fact that people in the said field communicate at the expert level, and the related need for such a selection of linguistic means from the ethnic language in which communication takes place that its users communicate efficiently in the field of professional communication. The knowledge of these conditions will enable the reader to approach the relationship between language and the so-called professional language with greater understanding.