The aim of the article is to analyze the scientific linguistic dictionaries of the early 21st century that describe the poetic and scientific heritage of Mikhail Lomonosov and the rhetorical system he proposed, in terms of the heuristic possibilities that these lexicographic experiments provide to the researcher of the Lomonosov language and style. The research material is five editions of the academic Dictionary of the Language of M. V. Lomonosov, the dictionary Rhetoric of M. V. Lomonosov. Tropes and Figures, the second volume of the Syntactic Dictionary of Russian Poetry of the 18th Century. The main methods are general scientific (analysis, synthesis, inductive and deductive, comparative, quantitative) and specific philological (contextual, comparative-descriptive, functional-descriptive, etc.). The analysis showed that a series of vocabulary materials created by the project team of the Institute of Linguistic Research, Russian Academy of Sciences, made an important contribution to the comprehensive description of Lomonosov’s poetry in terms of its metric and stanzaic repertoire, the rhyming system and the lexical and grammatical design of verse endings, presentation of individual groups of vocabulary participating in the formation of the scientific and odic styles of the middle of the 18th century. Using the example of the lexicographic description of the word azure, the author of the article reveals the rich informative potential that a researcher can extract from Volumes 1-5 of the Dictionary of the Language of M. V. Lomonosov. The data of the dictionary show the frequency the word has, the range of its meanings, grammatical variants, the genre and stylistic range of the use of the word in Lomonosov’s works, the word’s participation in the rhyme lexicon, the rhythm-metric organization of Lomonosov’s poetic experiments. The analysis of the lexeme azure allows the author of the article to come to the conclusion that it was not Lomonosov’s poetic practice but his scientific work that contributed to the consolidation in the general literary use of the feminine gender of azure. Comparison of the Rhetoric of M. V. Lomonosov. Tropes and Figures and the materials of the Syntactic Dictionary of Russian Poetry of the 18th Century proves the closest connection between the rhetorical theory set forth in the Rhetoric and Lomonosov’s own poetic practice: all the tropes and figures Lomonosov described are found, albeit with varying frequency, in his poetry. In addition to the devices of “decorated” speech presented in the Rhetoric, Lomonosov also uses others that are not mentioned in the Brief Guide to Eloquence as special phenomena, and this confirms the idea of the poverty of any classifications in comparison with real literary practice. Lomonosov dictionaries make it possible to present in a systematized form many features of the idiostyle of the poet and scientist, to highlight the stages of the formation of general literary, general poetic, genre and individual norms of the era of linguistic reforms, to clarify and check many of the theoretical principles concerning the evolution of Russian literature. The author declares no conflicts of interests.