The article aims to demonstrate how the creators of the "Explanatory Dictionary of the Russian Language" (edited by D. N. Ushakov) sought to describe the vibrant, pulsating nature of the post-revolutionary language at the stage of transition from one era to another at the time of the new culture birth. The technological progress and the change of the social system in Russia led to significant changes in the lexical and semantic system of the Russian language: new lexemes appeared, reflecting shifts in the scientific, technical, political, social and cultural spheres of life; new lexical formations emerged in the language (numerous compound words, abbreviations, etc.); there was a change of style (for example, the vocabulary of the belles-lettres style , especially words associated with religious culture, acquired a lower ironic, mocking or contemptuous stylistic coloring). The dictionary creation circumstances under the conditions of strict ideological control entailed the need to use special marked vocabulary. Ideologized definitions arose concerning the political concepts and realities that appeared after 1917.The article also describes the characteristic features of this lexicographic masterpiece, on the one hand, reflecting the lexico-semantic system of its time, and on the other hand, preserving the vocabulary of the passing era. It is shown how difficult it was to construct clear boundaries between the old and the new in lexicographic form. In some cases, the compilers could not keep to the rigor of the design, and this led to inconsistencies and even contradictions. Special attention in the article is paid to the words marked with the notes "nov." (new), "zagr." (foreign) and "dorevolyuc." (pre-revolutionary). A separate mini-essay is devoted to the definitions of the headwords perevorot (coup) and revolyuciya (revolution). It is noted that the inclusion of supplementary information from various fields of culture and science allows talking about the use of the interdisciplinary approach elements that are ahead of their time.As a result of combining three absolutely different layers of vocabulary and providing their innovative description in one dictionary, there was borne an absolutely unique lexicographic masterpiece.