The article deals with the problems of synonymy in verbal dialect lexis based on the material of Smolensk business writing of the 17 th – 18 th centuries, the time of buoyant lexical norms formation in the Russian literary language. The author draws attention to the fact that some of the dialect verbs do not enter synonymic relations and researches into the reasons for the absence of their synonyms. Extensive lexicographic material of the Russian, Belarusian, Ukrainian and Polish languages was involved, as well as data from monographic studies on the topic. It has been proved that this is often not only the original dialectal lexemes, but also the lexis borrowed from Western European languages through the Polish transmitter language, which can be considered a specific feature of Smolensk verbal synonymy in the period of the 16 th – 18 th centuries. The causes for restricted inclusion of dialect verbs into synonymic relations are the following: the semantics of dialect verbs contains some additional shades of meaning, which are not represented in the lexis of the literary language, they are expressed with the help of descriptive means, for instance, particularizing words; words viewed as potential synonyms, are noted to demonstrate hyponymic relations; the semantics of dialect lexis reveals diffusive character. The cases are described, when unclear meaning of the dialect verb in the limited context prevents it from the inclusion into a particular synonymic row. The dynamics of dialect lexis is characterized. It is represented in the loss or preserving some lexical units in the lexis of modern Smolensk dialects.