Recently, linguistic literature has increasingly focused on the problems of the language of science. This research is devoted to the problem of synonymy in the field of phonetic terminology of the period of its formation (XVIII - early XX centuries). The article describes various synonymic series of phonetic terms, the main reasons for synonymy are considered. The source of the material was a number of works on Russian grammar, which includes the work of domestic linguists: M.V. Lomonosov, A.A. Barsova, N.G. Kurganova, A.Kh. Vostokova, N.I. Grech, G. Pavsky, K. Aksakov, V.A. Bogoroditsky, F.F. Fortunatova, I.A. Baudouin de Courtenay, A.A. Potebni and others.
Keywords: synonymy, synonymy in the field of phonetic terminology, synonymous series of linguistic terms, reasons for synonymy in terminology.