The article describes and analyzes words with the ancient root жи(ть), which have undergone terminologicalisation. Nowadays, the focus of the research is the issue of the terminological vocabulary influence on the development of language as a whole. In order to reveal the semantic potential of the words with the root жи(ть), we studied these words in biological and medical terminology. The subject of our study is focused on the semantics of these words, since biology studies different aspects of life of living beings, medicine is concerned with healing people, and the words we are interested in denote signs, actions and processes related to all animate things. The research material is based on dictionaries of biological (botanical, zoological) and medical terms, explanatory dictionaries of the Russian language, which reveal the semantic scope of the words of interest and provide interpretations of their meanings. The research was carried out using the descriptive method and the method of dictionary definitions. We considered the word-forming and semantic features of the words with the root жи(ть) serving as names of different scientific objects (plants and animals), phenomena, features, properties, methods, actions and processes using the material of biological and medical terminology. The article describes the interaction and interpenetration of common and terminological words and identifies two-component terminological word-combinations, in which words with the given root are used, to define objects at the level of species nomination. As a result of the study, we found more than one hundred medical and biological terms with the root жи(ть); determined terminological word-formation chains; highlighted the terminological homonymy and sub-spheres in biological and medical terminology (botanical, zoological, entomological and pharmaceutical), in forensic medicine, space medicine, etc. We have come to the conclusion that the words with the root жи(ть) are used to nominate plants, living organisms, processes in living organisms, biological formations, abilities of living organisms and diseases.