In the article the issue of singling out some systemic criteria of differentiation between the fundamental and applied terminologies is considered. The authors point at the fact that each terminology has its own individual peculiarities, which mark it out against a general background of the terminological fund of a certain language. It is asserted that one of the most important and effective criteria that can be the basis of the approach to the study of sublanguages for special purposes is a (...) fundamental or applied character of the sphere of professional or scientific knowledge verbalized by a certain terminology. Such terms, as ‘fundamental terminology‘, ‘applied terminology‘ and ‘terminology of transition type‘, are introduced for scientific use. The fundamental terminology is understood as a sublanguage for special purposes that verbalizes the notions, forming the totality of fundamental knowledge, serving for the description of phenomena and processes in reality and in science, in the framework of which the fundamental research is carried out. The applied terminology is the name for the sublanguage for special purposes representing the notions, in which the results of human being’s practical scientific-industrial activity for changing the reality, forming the artificial habitat, are conceptualized. The terminology of transition type is the terminology that verbalizes the fragments of the field of scientific knowledge in which the research can have both a fundamental and applied character. The authors come to the conclusion that pure applied or fundamental terminologies are quite rare, that it is rational to speak about the degree of manifestation of the applied or fundamental character within the limits of this or that terminological system. (shrink)