Introduction. The paper focuses on the linguistic concepts of terminology and a term system, provides the views of linguists on the definition and differentiation of these terms, explains the semantics of the word and the term, as well as the role of the cognitive approach in modern terminology. The scientific work defines a concept and a category, and describes the role of the processes of conceptualization and categorization in English terminology. As more than 90 % of new words appearing in modern languages is vocabulary for special purposes, it is increasingly important to study the ways of their formation. The research is relevant since it provides a deeper understanding of the structure and content of concepts that underlie the formation of language categories, the mechanisms of interaction between cognitive and language structures in the process of forming the terminological meaning.

Methodology and sources. In light of the cognitive approach to understanding the semantics of a word the authors emphasize anthropocentrist thinking, language picture of the world and lexical-semantic variants of the word. The cognitive approach allows us to reveal the causes and mechanisms of dynamic processes in the field of professional nomination, taking into account the changing cognitive and communication needs of people. The research is made using corpora data.

Results and discussion. It has been found out, that cognitive categories are linked to conceptually defined prototypes that are crucial for the formation of categories. The necessary to define the central elements of prototypical categories has been proved, as they make the category logical, understandable and convenient, since all members of the category meet a given list of characteristics. As a result of the research it has been proved that in an investment terminological system a prototype turns out to be the best representative of a category.

Conclusion. It has been concluded that the study of conceptualization and categorization processes is extremely important when analyzing terminological systems in general, and investment terminological system of English, in particular, because it allows to identify the basic concepts underlying the formation of terminological systems. The study of the principles and mechanisms of categorization of language units makes it possible to identify and analyze their prototypical semantics in terms of their common properties with the prototype of the category. This possibility is of paramount importance for research in the field of cognitive linguistics, since it is the prototypical semantics of language units that largely determines their use in a sentence to convey a particular meaning.