The article is devoted to the comparative terminological analysis of approaches to scientific review of concepts “subject” and “subjectness” in Ukrainian and foreign psychology, the author's interpretation of these concepts, defining how they translate into English, and reverse translation of relevant terms. The basic concepts of subjectness in Ukrainian (V.A. Romenets, V.O. Tatenko) and Russian (S.L. Rubinstein, A.V. Brushlinsky, K.O. Abulkhanova) psychology, the connection of a full-fledged subjectness with intelligence according to O.F. Losev, as an attempt to transform the imperfections of life are analyzed. The terms of subject-development paradigm, subjectogenesis, responsiveness of the subject as a response to the call for socio-cultural development are considered. It is shown that the terms “agent” and “agency” are widely used in foreign scientific and psychological discourse, which are often translated into Ukrainian as “subject” and “subjectness”, and sometimes as “subjectness activity” (the reverse translation looks accordingly). The authors' critical attitude to such variants of translation of these terms is substantiated, and other variants of translation which are already widely used in modern science are offered, namely “subject” – “суб’єкт”, “subjectness” – “суб’єктність”, “subjectness activity” - “суб’єктна активність”. The formation of the terms "subject" and "subjectness" in foreign scientific discourse is considered. The author's understanding of the subject as a carrier of the mental model of the world, and the corresponding interpretation of subjectness are offered