The article touches upon controversial issues of Adyghe etymology and semantics, as well as his-torical phonetics, concerning the nature and structure of root morphemes, which have not been comprehensively resolved to date. The existing approaches to the study of root morphemes, which have received their coverage in the works of scientists such as M.A. Kumakhov, A.K. Shagirov, N.R. Ivanokov, N.F. Yakovlev, do not seem to be definite and require clarification. This paper of-fers a different view of the problem raised and its original solution from the existing approaches. The root morphemes considered in the work, grammaticalized in diachrony, in the course of the presented etymological and semantic analysis, reveal traces of acoustic and semantic mutagenesis, which generally affects the further development of the lexical system of the language. For the first time, the term acoustic mutagenesis was introduced into scientific circulation, by which we mean the mutation of sounds in modern Adyghe and Kabardian languages while maintaining the same meaning or close to the original meaning. In the course of semantic evolution, the loss of one se-mantic meaning in the root element does not entail its consolidation in the structure of lexical in-novations, its clear state in a situation of preposition or postposition. Root morphemes, distin-guished in modern language as affixes, were at the same hierarchical level in the proto-language, and their position in the preposition only indicates their attachment to the rest of the root ele-ments, the position in the postposition indicates the opposite.