The topic of the research for this dissertation is morpho-syntactic equivalence in translation, using the example of the Ukrainian infinitive in translation to Polish, while the goal of the research is a description of the possibilities for translation equivalence, expressed via a morpho-syntactic lens. The empirics gathered, as well as the results of the analysis conducted, might serve in the future as a database for continued research into the subfield of cognitive linguistics, and more particularly, applying in-depth semantic analysis, into the question, raised in that field of linguistics, of the cognitive functions of parts of speech. Moreover, the results of the analysis might find practical application in the field of glottodidactics, in preparing a Polish language handbook together with exercises for users of the Ukrainian language. The following research methods have been applied in this investigation: 1) the distributional method; 2) statistical description; 3) the survey method, using a questionnaire. As regards the theoretical foundations of the research project implemented in the preparation of this doctoral dissertation, the foremost place is occupied by the concept of isomorphism, as one lens for researching translation equivalence on a morpho-syntactic level. This dissertation adopts the concept of isomorphism proposed by John Lyons (Lyons, 1968). The structure of the dissertation is as follows: introduction, three core parts - part I is theoretical, parts II and III are empirical - and an additional part IV, conclusion, bibliography, a reference list of acronyms and symbols, a list of charts and diagrams, and the abstract in English. The first part of the dissertation is divided into two theoretical sections. The first of them concerns the general characteristics of the Ukrainian infinitive, with attention being paid to the category of infinitive and the general historical background of that form. Moreover, a comparative description is provided of the syntactical functions of the Ukrainian and Polish infinitive. In the second section attention is concentrated on the noun in the Polish language as one of the possible translation equivalents for the Ukrainian infinitive. Here the matter of noun classification and the phenomenon of nominalization are discussed. Particular emphasis is placed on animate nouns (nomina actionis) that came about on the basis of syntactic derivation. In that part of the dissertation I adopt the division of deverbal derivatives proposed by Jadwiga Puzynina, i.e. substantiva verbalia and substantiva deverbalia (Puzynina, 1969: 28). Both types are described, focusing on the rules for creation of deverbal nouns. In the final part of the section, I present the characteristics of deverbals in the Ukrainian language for comparison with Polish. In part II of the dissertation attention is focused on translation equivalents of the Ukrainian infinitive in isomorphic and partially non-isomorphic translation. In section I of that same part of the dissertation, I present the possible equivalents of Ukrainian infinitive phrases with verbs and nouns as a constituent element, while in section II, I discuss equivalents of infinitives in complex sentences, and of infinitives that are an independent component in the sentence. In both sections, I pay attention to the phenomenon of isosyntacticism and non-isosyntacticism. Part III of the dissertation concerns the translation equivalent of the Ukrainian infinitive in entirely non-isomorphic translation. Section I describes the noun as the most commonly encountered equivalent of the Ukrainian infinitive in non-isomorphic translation. I also raise the issue of isosyntacticism and non-isosyntacticism in that type of translation. Section II consists of a description of the remaining means of non-isomorphic translation of the Ukrainian infinitive. Moreover, attention is given to the phenomenon of non-isomorphic translation with compensation and to descriptive equivalents. Part IV of the dissertation, which constitutes a supplement to the core parts, documents the survey research conducted as a complement to the core considerations, with the goal of demonstrating the possible tendencies in translation of the Ukrainian infinitive to Polish by native speakers of the Polish language. The conclusion contains a summary of the morpho-syntactic analysis performed, along with statistical data, and also presents the possibilities for further linguistic research. The shares, in percentages, of all possible translation equivalents of the Ukrainian infinitive (taking into account the absolute lack of an equivalent) are as follows: 1) infinitive (82,64%); 2) finite verb form (6,05%); 3) Substantiva verbalia deverbal noun (4,98%); 4) Substantiva deverbalia deverbal noun (1,37%); 5) descriptive equivalent (1,21%); 6) adverbial participle (0,59%); 7) deverbal noun - secondary meaning (0,54%); 8) noun formed on the basis of a semantic derivation (0,40%); 9) compensation on the level of content Ø (0,40%); 10) adjectival participle (0,29%); 11) impersonal form of the verb (0,21%); 12) adverb (0,08%); 13) '-no' and '-to' forms of the verb (0,08%); 14) adjective (0,03%); 15) pronoun (0,03%); 16) preposition (0,03%); 17) no equivalent (1,07%). The focus of considerations related to translation studies on the morpho-syntactic equivalence of the source text and target text (Ozga 2011; Szumska, Ozga, 2020) might serve as the empirical basis for continued research in the field of cognitive linguistics, and cognitive grammar more precisely, based, among other things, on the assumption of a relationship taking shape between the profiling of the information transfer function, and the parts of speech utilized.
