Abstract: The object of the research is the development history of the terms of European moral philosophy. The subject of the research is the transformation of ethical terms in the XVIIth century which started the process of formation of a modern definition of 'morals' and assimilation of traditional concepts and semantics of moral philosophy. In his research Sochilin examines theoretical, textological, historical-philosophical and institutional contexts of this process. He also describes the origin and historical dynamics of such terms as 'morals', 'ethics', 'moralitas', 'moralia', 'jus naturale', 'lex naturalis', 'honestum', 'honestas' and 'rectitudo'. The research methods include linguistic and general humanities methods such as analysis of the semantic extension of the aforesaid terms, their morphemic analysis and contextual analysis. The researcher relates these terminological transformations to conceptual changes in European moral philosophy. As a result of the research, the author clarifies etymology of the terms 'morals' and 'ethics' and compares them to their Latin and Greek originals. The author explicates similarities and differences in their origin, concludes that the term 'moralitas' has a crucial importance for the formation of today's definition of morals and describes the theoretical grounds thereto. He defines the two interdependent philosophical traditions the aforesaid process was part of (natural law tradition and Thomist tradition with primary Aristotelian ethic terminology) and outlines the scope of texts of the XVIIth century the process could be seen in. The author has also summarized historical dynamics and developed the five-level program for further research.