The article deals with professional discourse which is defined as a speech in the aspect of the event, permeated with extralinguistic, sociocultural, psychological, professional and other factors, as a verbal communication aimed at theoretical and practical business problems solution and requiring special training and experience in a definite sphere of activity. The situation in professional discourse is a kind of professional knowledge presentation depending on the participants’ personal experience. The structure and the main functions of professional discourse are revealed. The fixed and stereotyped character of any professional activity gives a solid ground for professional domains conceptual linguistic modelling, viewed as a base for languages for specific purposes ideographic description. The linguistic modelling can be carried out within the framework of cognitive spheres I. “Nature”. II. “Man”. III. “Society”. IV. “Cognition (a priori)”. The developed professional discourse description model could serve both the needs of the anthropological theory of language and the need to improve the practice of professional communication in different fields.