This article describes the  study of the topic synonymy and rhythm in the works of domestic and foreign linguists. Synonymy demonstrates the richness and diversity of the language. The presence of a large number of synonyms creates ample opportunities for the transmission of thoughts and feelings, makes speech flexible and expressive. The richer the lexical synonymy, the more possibilities of semantic expression, the higher the expressive potential of the language. N. M. Karamzin considers synonyms a source of language enrichment:"