This doctoral thesis is mainly concerned with the two phenomena that present the main problems to the attempts of terminology standardization – polysemy and synonymy, which are considered in the light of descriptive, sociocognitive aspect as traditional terminology principles turned out to be insufficient for their analysis. The thesis starts with theoretical framework that provided the author with the efficient models to be used in further analysis. Within the theoretical chapter, the special language has been identified as the subset of the general language and not its variant. Such a position of the special language implies that it shares the rules with the general language, but has also additional specific characteristics referring to a special subject field, users and communicative situation. Sociocultural function of the language can be identified in the process of choosing a term that depends on the user's level of specialized knowledge and on the given communicative situation, which is also related with use of the special language in different functional styles. Such a perception of a special language has been the basis for the research of terminological variability depending on context. The research is based on vertical classification of a special language, whereby the author used a corpus of texts of various degrees of specialization which imply heterogeneity of users. Corpus of texts used for this research consists of translations belonging to financial subject field. Terminological analysis of Croatian financial terminology was carried out first, whereby a large amount of anglicisms was established. Most of them either do not have an equivalent term in Croatian or they co-exist with an equivalent Croatian term thus making a synonymous pair or even synonimous sequence. Frequency distribution of both or more coexisting terms was compared in the corpuses, which gave answer to whether the coexistence of those synonyms is justified or, on contrary, the terms should be standardized. Legitimacy of the coexistence of synonyms results from cognitive motivation underlying their choice in a specific situation, which gave rise to the application of sociocognitive theory in the further research. Apart from synonymy, terminological analysis also showed the existence of polysemy in Croatian financial terminology. The analysis of polysemous units was carried out from the aspect of cognitive linguistics, based on prototype theory. The author carried out the analysis of polysemous structure of lexemes belonging to general language and on terms belonging to special language, which resulted in observation that the processes causing polysemy and the structures of polysemous units in special language are equal to those in general language. Different contexts activate different aspects of meaning of a single notion, which proves pluridimensionality of notion and polysemy of term. Since polysemy presents one of the main threats to an accurate translation, attempts made to reduce it both in theory and in practice are presented in the last part of the chapter. Approach based on cognitive linguistics was afterwards applied to the examples of synonymy, taking into consideration user's construal of meaning which is based on his or her extralinguistic experience and perception which leads to semantic change, i.e. the context activates the existing aspect of meaning or causes the appearance of the new one. The examples show whether different perspectives of the users, their different intentions or different idealized cognitive models can influence the choice of a particular terminological variation, what would lead to the assumption that the same concept can be described from different points of view even though it belongs to the domain of specialized knowledge. The second part of the synonymy analysis put an accent to a corpus analysis which showed conceptualization processes based on which the users choose particular terminological and lexical variations and put them in a synonymous relationship. Contribution of this thesis lies in treatment of polysemy and synonymy as functional, cognitively-motivated characteristics of terminology, and in descriptive, sociocognitive aspect of the approach to their research.