The Explanatory Dictionary of the Russian Language by D. N. Ushakov and his colleagues, published between 1935 and 1940, is the first major dictionary of the post-revolutionary era, reflecting the lexical composition of both the literary and colloquial speech of educated people in the new Soviet Russia. It characterized the individual of the new social order and recorded emerging linguistic norms. The aim of this article is to present this dictionary as a potential source for the study of ethnolinguistic vocabulary. It is demonstrated that Ushakov’s work not only fulfills all the normative functions of an explanatory dictionary but also objectively contains a significant amount of dialectal vocabulary, as it was still in demand among speakers of that time and naturally of interest to ethnolinguists. The extensive system of stylistic and emotionally expressive labels in the dictionary today aids in identifying, on the one hand, new vocabulary from the Soviet era, and on the other, obsolete vocabulary that was still in use. Ushakov’s dictionary contains intriguing designations of Russian cultural realities, offering country-specific information that allows for a portrayal of Russian life. For this study, only subject-specific vocabulary was selected, using a random sampling method of words from certain groups reflecting ethnolinguistic content. The subsequent analysis of this vocabulary will enable the identification of the national and cultural specificity of the Russian language in the post-revolutionary era.